Bumagina, Natalyya Anatolyevna

Bumagina N.A., Ksenofontov A.A., Bocharov P.S., Antina E.V., Berezin M.B.

Multifunctional sensors are becoming increasingly important because a single such compound can be used to detect ions of two or more metals. We propose a 3,3′,4,4′,5,5′-hexamethyl-2,2′-dipyrromethene (HL) as multifunctional chemosensor for absorbance ratiometric detection of Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+ ions, and fluorescent detection of Zn2+, Cd2+ ions. The influence of the nature of complexing ion and medium on the thermodynamic stability of the [ML2] complexes, chromophoric and fluorescent responses of complexation reactions was analyzed. The lgKo values of [ML2] formation processes range from 4.72 to 11.08 and, regardless of the medium nature, increase in similar sequences of complexing agents: Cd2+, Ni2+, Hg2+, Co2+, Zn2+, Cu2+ – in the c-hexane/propanol-1 (30:1, v/v) and Cd2+, Hg2+, Co2+, Zn2+ – in DMF. The maximum fluorescent response (I/Io = 100–150) was observed for the reaction of dipyrromethene with Zn2+ ions. The reaction of HL with Cd(AcO)2 is accompanied by a 10-fold increase in fluorescence. Depending on the nature of the metal ion being determined and the medium, the detection limit of M2+ ions reaches 5 × 10−9–5 × 10−8 mol/L. Test-systems as HL-doped cellulose tablets were developed for detecting trace amounts of Zn2+ and Cd2+ ions in aqueous solutions. The using 3,3′,4,4′,5,5′-hexamethyl-2,2′-dipyrromethene as a multifunctional chemosensor, both chromophore detection of Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+ ions and "turn-on" fluorescent sensing trace amounts of Zn2+ and Cd2+ ions can be performed. Considering the significant differences in the chromophore-fluorescent characteristics of ligands and metal complexes, dipyrromethenes have great prospects for use in cation recognition.

Bumagina N.A., Krasovskaya Z.S., Ksenofontov A.A., Antina E.V., Berezin M.B.

A wide range of dipyrromethenes (17 objects) with different nature, number, and attachment positions of alkyl, aryl, and meso-aza substituents was synthesized, and the effect of molecular structure features on their spectral properties was analyzed. It is shown that, chromophores absorb in a wide spectral range from ∼ 420 to ∼ 600 nm due to the structural modification of the dipyrromethene ligand backbone. Partially alkylated dipyrromethenes containing 4–5 methyl substituents absorb in the region from 421 to 436 nm. For fully alkylated dipyrromethenes, the band maximum position shifts to the region from 437 to 446 nm for ligands with 4,4′-substituents in the sequence: methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl. The most significant spectral responses in the form of a red shift of 100 nm (in DMF) are observed when four methyl substituents in the 3,3′,5,5′-positions are replaced by phenyl groups. The replacement of the methine meso-spacer by a nitrogen atom leads to an additional red shift by another 70 nm. Particular attention is paid to the comparative analysis of the effect of structural factors on the coloristic and spectral responses of the complexation of dipyrromethene ligands with zinc(II) acetate and the stability of the resulting complexes [ZnL2], for which the lgKo values are varied from 6.4 to 10.9. The auxochromic action of Zn2+ cations shifts the band maxima of electronic absorption spectra to the long wavelength region by 20–76 nm relative to the spectra of the ligands. The highest complexation constant lgKo is 10.9 was obtained for the reaction of Zn(AcO)2 with hexamethylsubstituted dipyrromethene. Ligands with partially methylated pyrrole nuclei and extended alkyl and benzyl substituents form less stable complexes. The greatest effect of lowering the [ZnL2] stability is produced by the introduction of an electron-withdrawing aryl substituent into the meso-spacer of the dipyrromethene ligand (lgKo is 6.4).

Bumagina N.A., Antina E.V.

Content assessment of metal ions (analytes) in solutions, industrial waters and natural objects is one of the most important tasks in biochemistry, medicine, ecology and various industries. To solve this problem, new types of highly sensitive and selective analytical probes are being developed. The most promising areas of analytical control are based on the bright coloristic and fluorescent responses of the complexation reactions of the probe with the analyte. Various classes of fluorescent dyes have been successfully used to obtain such probes. Among them, BODIPY fluorophores are of particular interest due to the manifestation of intense spectral-luminescent and other practically significant properties. The review focuses on advances in the development of chromo-fluorogenic BODIPY probes containing various receptor fragments selective for cations of individual s-, p-, d- or f-elements. Probes work by various mechanisms, such as photo induced electron transfer (PET), internal charge transfer (ICT), fluorescence resonance energy transfer (FRET) and others. Ultimately, the reaction of the probe with the analyte results in significant fluorescent "Off-On" or "On-Off" responses. The review contains several sections in which fluorescent BODIPY probes were divided into groups of detectable s-, p-, d- and f-elements. The spectral properties of BODIPY probes, their chromo-fluorogenic, including ratiometric, responses when binding to the analyte being determined in solutions, the binding efficiency, as well as the selectivity of determining the analyte are discussed. In addition, in many cases the possibility of practical use of probes for the analysis of metal ions in aqueous, aqueous-organic media, and cells was shown.

Bumagina N.A., Ksenofontov A.A., Antina E.V., Berezin M.B.

This study presents a dipyrromethene-based sensitive and selective probe for Zn2+ ions detection in aqueous and water-organic media. The probe demonstrates absorbance-ratiometric and “off-on” fluorescent sensing for Zn2+ in a DMSO/H2O (9:1, v/v) mixture. The 2,2′,3,3′,4,4′-hexamethyl-2,2′-dipyrromethene (HL), similar to its analogs, exhibits weak fluorescence (with a quantum yield of less than 0.001). However, upon the presence of Zn2+ ions in the sensor HL solution, there is a remarkable increase (up to 200-fold) in fluorescence intensity due to the formation of a stable intramolecular chelate complex [ZnL2]. This complex formation induces a significant hyperchromic effect and a red shift (57 nm) in the characteristic absorption bands. The sensing mechanism of the probe towards Zn2+ ions was thoroughly investigated through absorbance and fluorescent titrations, molar ratio plots, 1H NMR, and DFT/TDDFT studies. The fluorescence response exhibited a strong linear relationship with Zn2+ concentration within the range of 0 to 5.7 × 10–6 mol/L. The detection limit (LOD) and limit of quantitation (LoQ) for Zn2+ were determined as 2 × 10–8 mol/L and 6.6 × 10–8 mol/L, respectively. Moreover, the probe demonstrated high selectivity for Zn2+ ions over other metal ions (Na+, Mg2+, Al3+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Pd2+, Cd2+, Hg2+, Pb2+). Test systems in the form of test-strips and cotton-pads were developed based on the dipyrromethene sensor for rapid “naked-eye” detection of zinc ions in water. The sensor was successfully applied for detecting Zn2+ ions in real water samples.

Bumagina N.A., Antina E.V., Ksenofontov A.A., Antina L.A., Kalyagin A.A., Berezin M.B.

• The BODIPY modification have a very significant effect on the photophysical properties. • Alkyl-BODIPYs absorb at 490–535 nm and fluoresce at 500–550 nm ( Ф F from 70 to 100%). • Fluorescence quantum yield of Br- and I-BODIPYs was decreased due to the “heavy atom” effect. • The attachment positions of the aryl substituents in the BODIPY determine their properties. • The NIR-BODIPYs (to 1000 nm) were obtained by meso -aza, benzo-fused and oligo-modification. The review considers the results of research by scientists from different countries in the field of synthesis and photophysical property study of known BODIPY. We focus on describing the main ways the BODIPY structure modifying by substituting the pyrrole rings, the meso -spacer, and the boron atom of the indacene core with different nature substituents and changing the spectral and other practically significant BODIPY properties associated with a particular type of their modification. In addition, we have considered the effects of alkylation, halogenation, nitration, amination, and arylation at the meso -spacer and/or pyrrole rings, boron atom; pyrrole rings annulation; meso -aza-substitution, covalent oligomerization through direct σ-bonds or spacers. Most of these approaches have a very significant and individual effect on the photophysical properties, hydrophobicity or hydrophilicity of dyes and consequently, on their practical application possibility. In the general case, BODIPY modification approaches considered above make it possible to vary the absorption and fluorescence bands position of BODIPY in the range from UV to NIR spectral regions (from 400 to 1000 nm). Depending on the features of BODIPY functionalization, as well as on the properties of the medium, the quantum yields of fluorescence, phosphorescence, and singlet oxygen generation of BODIPYs can be changed from 0 to 100%.

Antina L.A., Bumagina N.A., Kalinkina V.A., Lukanov M.M., Ksenofontov A.A., Kazak A.V., Berezin M.B., Antina E.V.

Red-emitting distyryl substituted BODIPY dyes are among the most promising luminophors for bioimaging and optics applications. However, the practical application of BODIPYs is limited due to their high hydrophobicity and tendency to aggregate in aqueous organic solutions and solid phase. In this article, we propose an elegant solution to this problem. To this end, we carried out the detailed experimental and quantum-chemical study of the structural and spectral features of BF2-ms-phenyl-5,5'-bis(4-dimethylaminostyryl)-3,3'-dimethyl-2,2'-dipyrromethene (distyryl-BDP). The particular attention was paid to analysis of high sensitivity of the distyryl-BDP spectral characteristics to the solvent properties, and also the aggregation behavior features both in water-organic media and in mono- and multilayer Langmuir-Schaefer films. We selected the best conditions to obtain the hydrophilic micellar structures of distyryl-BDP with Pluronic® F127 having a high efficiency of dye solubilization. This method increasing the solubility improves the distyryl-BDP transport efficiency in physiological aqueous media. The aqueous solutions of distyryl-BDP-Pl micelles show the intense fluorescence in the phototherapy window region (λfl = 739 nm).

Bumagina N.A., Antina E.V., Krasovskaya Z.S., Berezin M.B., Ksenofontov A.A., Vyugin A.I., Semeikin A.S.

• The chromo-fluorogenic dipyrromethene chemosensors were proposed for Zn 2+ detection. • Reaction of Zn(AcO) 2 with dipyrromethene chemosensors is accompanied by almost 100-fold fluorescence buildup. • The dipyrromethene chemosensor is characterized by high selectivity of fluorescent Zn 2+ detection. • The detection limit of Zn 2+ ions using a dipyrromethene chemosensor reaches 4·10 –8 mol/L. • New test-systems were developed for the express analysis of Zn 2+ ions in aqueous media. The dipyrromethene derivatives as new chromo-fluorogenic chemosensors for quantitative detection and express analysis of Zn 2+ ions were synthesized and structural characterized. The sensing process of dipyrromethene toward Zn 2+ was evaluated by UV–vis and fluorescence spectroscopy, molar ratios plots, and DFT calculations. The complexation of Zn(AcO) 2 with dipyrromethenes in DMF solution was accompanied by significant bathochromic and hyperchromic effects in the electronic absorption spectra due to the formation of [ZnL 2 ] complex. The 1:2 (Zn:HL) binding mode was proposed on the basis of absorption and theoretical studies. The complexation constants (lg K o ) of Zn(AcO) 2 with dipyrromethenes are from 8.1 to 10.9, which implying the potential of dipyrromethenes to acts as selective chemosensors for Zn 2+ . It is shown for the first time that the hexamethyl-substituted dipyrromethene could recognize Zn 2+ ions in DMF solution through significant (almost 100 times) “off–on” fluorescent response caused by Zn 2+ and visible color change from yellow to bright green under UV irradiation induced by formation of [ZnL 2 ]. Hexamethyl-substituted dipyrromethene had high selectivity towards Zn 2+ ions over many environmentally relevant ions, and high sensitivity with the detection limit in nanomolar level (4·10 –8 mol/L). In terms of the thermodynamic constant and the fluorescence response of the complexation reaction of [ZnL 2 ], as well as the detection limit of Zn 2+ ions, dipyrromethene HL 2 surpasses many Zn 2+ sensors known in the literature. Dipyrromethenes can be a tool for detecting Zn 2+ ions with simple test strips.

Antina E.V., Bumagina N.A., Berezin M.B.

Compounds with an open chain tetrapyrrole structure are mainly formed in plant and animal organisms during the catabolism of heme or other natural macrocyclic tetrapyrroles. Great success has been achieved in the development of synthetic open-chain analogs of natural tetrapyrroles with a successful combination of practically useful properties. Various combinations of several types of modifications in terms of the method, the nature of the attachment of the spacer and peripheral substituents make it possible to obtain compounds with the necessary set of properties, required for specific practical purposes. Bis(dipyrromethene)s are characterized by conformational isomerism. Depending on the preferred conformation, the bis(dipyrromethene) ligands form complexes of different structure and composition upon complexation with cations of some elements. Bright coloristic and fluorescent signals of the complexation processes of such ligands with metal cations are of great practical interest. The review discusses the possibilities of using bis(dipyrromethene)s as colorimetric and fluorescent sensors of amines and zinc, cadmium, and mercury cations. The review highlights prospects of using bis(dipyrromethene) complexes in various fields of medicine, laser technology, supramolecular chemistry, etc. • Open-chain tetrapyrroles form a huge class of compounds with a variety of useful properties. • Bis(dipyrromethene)s with cations of some elements form complexes of various structures. • Open-chain tetrapyrroles and their complexes exhibit intense absorption and, in some cases, bright fluorescence. • Bis(dipyrromethene)s are effective fluorescent sensors of amines and Zn 2+ , Cd 2+ and Hg 2+ . • The bis(dipyrromethene) complexes are perspective markers, components of supramolecular structures, laser devices and PDT .

Kuznetsova R.T., Aksenova I.V., Bashkirtsev D.E., Prokopenko A.A., Pomogaev V.A., Antina E.V., Berezin M.B., Bumagina N.A.

In the present paper spectral–luminescent, lasing, photochemical, sensory, and photosensitized characteristics of a number of Zn(II) and B(III) coordination complexes of dipyrrins with different structures are investigated. The results show that alkyl-, phenyl-, and propargylamino-derivatives of dipyrrin core in these complexes have excellent luminescent characteristics and can be used as active media for tunable liquid and solid-state lasers. Zinc (Zn-dpm 2 ) and boron fluoride complexes of dipyrrins (BODIPYs) with halogen atoms and aza-substitution in meso- position in their ligands do not exhibit effective fluorescence, but some of them have long-lived emission due to increased nonradiative intersystem processes in an excited state proceeding by the mechanism of heavy atom and the presence of low-lying nπ- and σπ-states of different natures and multiplicities. The reason for the short-wavelength shift of the Zn-dpm 2 spectra compared to the corresponding BODIPY is studied using quantum-chemical calculation. For solid samples based on halogenated complexes, a dependence of the long-lived emission intensity on the oxygen concentration in the surrounding gas mixture is established that indicates the possibility of application of these complexes for the creation of optical oxygen sensors. Moreover, results of investigations of halogen-substituted tetraphenyl-aza-BODIPY complexes as photosensitizers of singlet oxygen production are presented. Such complexes are promising for creating media for generation of singlet oxygen, which is important for photodynamic therapy and oxidation catalysis. In addition, data on the stability of these compounds in different electronic states are presented.

Antina E.V., Rumyantsev E.V., Dudina N.A., Marfin Y.S., Antina L.A.

The results of research on the correlation between molecular structure and spectral luminescent and photophysical properties for a new class of dyes and luminophores based on dipyrrins, bis(dipyrrins), and their coordination compounds in different media are summarized. The new perspective applications of dipyrrin dyes and luminophores as fluorescent sensors for measuring the polarity, viscosity, and temperature of the medium and highly sensitive and selective fluorescent “off-on” chemosensors for detecting Zn2+, Cd2+, and Hg2+ cations in weakly polar and nonpolar organic solvents and biological systems are discussed.

Aksenova I., Bashkirtsev D., Prokopenko A., Kuznetsova R., Dudina N., Berezin M.

In this paper spectral-luminescent, lasing, photochemical, and sensory characteristics of a number of Zn(II) and B(III) coordination complexes with dipyrrinates with different structures are presented. We have discussed relations of the structure of investigated compounds and formed solvates with their optical characteristics. The results showed that alkyl substituted dipyrrinates derivatives have excellent luminescent characteristics and demonstrated effective lasing upon excitation of Nd:YAG-laser. They can be used as active media for liquid tunable lasers. Zinc and boron fluoride complexes of dipyrrinates with heavy atoms in structure don't have fluorescence but have long-lived emission due to increased nonradiative intersystem processes in the excited state by the mechanism of a heavy atom. For solid samples based on halogenated complexes was found dependency of the long-lived emission intensity of the oxygen concentration in gas flow. The presence of line segment indicates the possibility of the use of these complexes as a basis for creation of optical sensors for oxygen. Moreover, results of a study of halogen-substituted aza-complexes under irradiation are presented. Such complexes are promising for the creating media for generation of singlet oxygen (1O2), which is important for photodynamic therapy in medicine and photocatalytic reactions in the industry.

Antina E.V., Dudina N.A., Berezin M.B., Guseinov S.S., Nikonova A.Y., V’yugin A.I.

The results of studies and comparative analysis of thermal properties and photostability of zinc(II) complexes with tetramethyl- and tetraphenyl-substituted dipyrrins and tetraphenyl-meso-azadipyrrin are reported. The thermal decomposition of complexes starts in the temperature range between 293 and 481°C depending on the molecular structure. Tetraphenyl-substituted zinc(II) dipyrrinate shows the highest photoand thermal stability. The substitution of phenyl moieties in the ligand structure with methyl groups and replacement of the methine spacer with a nitrogen atom reduces thermal stability and photostability of the complexes.

Nikonova A.Y., Kuznetsova R.T., Aksenova I.V., Tel’minov E.N., Mayer G.V., Dudina N.A., Nuraneeva E.N., Antina E.V.

The spectral luminescent, photophysical, photochemical, lasing, nonlinear optical, and sensor characteristics of a series of new synthesized complexes of zinc and difluoroborate with dipyrrines of different structure have been studied. It is found that many of these compounds exhibit stimulated emission in different solvents when excited by the second (532 nm) and third (355 nm) harmonics of a Nd:YAG laser in the range of 548–692 nm. It is shown that not only efficient fluorophores belonging to dipyrrine difluoroborates (with a quantum fluorescence yield close to 1), but also compounds with a fluorescence yield equal to 0.3, generate laser radiation with a high resource; phosphorescence is also observed along with fluorescence. Transmission of UV radiation (355 nm) is shown to decrease with an increase in the pulsed excitation power density; this is a manifestation of nonlinear optical properties. The change of phosphorescence signal in dependence of the composition of the gas mixture around a solid-state sample colored by dipyrrinate complexes indicates that a number of the compounds under consideration exhibit sensor abilities.

Dudina N.A., Antina L.A., Antina E.V.

New polymeric materials containing dinuclear double-stranded zinc(II) helicate with bis(1,2,3,7,9-pentamethyldipyrrin-8-yl)methane have been prepared on the basis of poly(methyl methacrylate) and tetraethoxysilane. The zinc(II) complex [Zn2L2] retains its fluorescence properties in a poly(methyl methacrylate) film. The photostability of [Zn2L2] in poly(methyl methacrylate) is higher by a factor of ≈2.5 than in the benzene solution. Conditions have been found for the preparation of [Zn2L2]-doped silicate matrix based on tetraethoxysilane via the sol–gel method. The [Zn2L2] complex in the tetraethoxysilane solid matrix shows a weak fluorescence with its maximum at λ = 545–549 nm.

Dudina N.A., Berezin M.B., Semeikin A.S., Antina E.V.

Boron(III) complexes with phenyl-substituted meso-aza-dipyrromethenes (one of them 4,4'-brominated) have been prepared. The bromination has resulted in weakening of the compound fluorescence by more than ten-fold. The studied complexes are stable for a long time in the solutions in non-polar solvents both in the dark and exposed to light. The bromine-containing complex rapidly decomposes in the polar media.

Zhou H., Gao S., Weng Z., Yuan L., Li W., Lei P., Li X., Yang Y., Yang M.

Glavaš M., Vidoša L., Mušković M., Ratkaj I., Basarić N.

Chakradhar S.P., Krushna B.R., Sharma S.C., George A., Salwe K.J., Kar B., Banu A., Kumar K.G., Manjunatha K., Wu S.Y., Nagabhushana H.

Islam M.M., Priya S., Kasana S., Kurmi B.D., Patel P.

Hentsch A., Guberman M., Radetzki S., Kaushik S., Huizenga M., He Y., Contzen J., Kuhn B., Benz J., Schippers M., Paul J., Leibrock L., Collin L., Wittwer M., Topp A., et. al.

Zhang W., Dong Q., Zhao Y., Yang W., Chen J., Xi F., Li Y., Liu X., Zhou J.

Ovchenkova E.N., Bichan N.G., Gruzdev M.S., Mozgova V.A., Chervonova U.V., Lomova T.N.

Grover V., Ravikanth M.

Ahmad H., Muhammad S., Mazhar M., Farhan A., Iqbal M.S., Hiria H., Yu C., Zhang Y., Guo B.

Wang X., Yu H., Tan F.

Shi F., Liu Y., Gao X., Wang Y., Zhang N., Yan J.

Krasnovskaya O.O., Spector D., Bykusov V., Isaeva Y., Grishin Y., Akasov R., Zharova A., Rodin I., Kuzmin V., Vokuev M., Nikitina V., Martynov A., Beloglazkina E.

AbstractLight induced release of cisplatin from Pt(IV) prodrugs is a promising tool for precise spatiotemporal control over the antiproliferative activity of Pt‐based chemotherapeutic drugs. A combination of light‐controlled chemotherapy (PACT) and photodynamic therapy (PDT) in one molecule has the potential to overcome crucial drawbacks of both Pt‐based chemotherapy and PDT via a synergetic effect. Herein we report green‐light‐activated Pt(IV) prodrug GreenPt with BODIPY‐based photosentitizer in the axial position with an incredible high light response and singlet oxygen generation ability. GreenPt demonstrated the ability to release cisplatin under low‐dose green light irradiation up to 1 J/cm2. The investigation of the photoreduction mechanism of GreenPt prodrug using DFT modeling and ΔG0 PET estimation revealed that the anion‐radical formation and substituent photoinduced electron transfer from the triplet excited state of the BODIPY axial ligand to the Pt(IV) center is the key step in the light‐induced release of cisplatin. Green‐light‐activated BODIPY‐based photosentitizers 5 and 8 demonstrated outstanding photosensitizing properties with an extraordinary phototoxicity index (PI)>1300. GreenPt prodrug demonstrated gradual intracellular accumulation and light‐induced phototoxicity with PI>100, thus demonstrating dual action through light‐controlled release of both cisplatin and a potent BODIPY‐based photosensitizer.

Ksenofontov A.A., Berezin M.B., Bocharov P.S., Khodov I.A., Miloshevskaya O.V., Antina E.V.

The search for fluorophores with intense absorption and emission in the red region of the spectrum is an important task, as such compounds can be used in fluorescence imaging, providing high image resolution due to the deep penetration of low energy photons into tissues. In this paper, we present the results of the synthesis and photophysical characterization of a novel ms-benzimidazole-4,4′,5,5′-tetramethyldipyrromethene bis(difluoroborate) (BOIMPY) compound, which exhibits intensive absorption and emission in the long-wavelength region while maintaining high fluorescence quantum yields (up to 60%). Using DFT analysis, we investigated the geometry of BOIMPY in both ground and excited states and described the influence of the molecular structure on its practically relevant photophysical properties.

Sherudillo A.S., Antina L.A., Lukanov M.M., Ksenofontov A.A., Dyshin A.A., Kiselev M.G., Berezin M.B., Antina E.V.

Li J., Zhang Y., Xu J., Jiang W., Weng Z., Li X., Yang Y., Gao S.

Li X., Du M., Ma C., Dong W., Ding Y.

A more flexible long-chain bis(salamo)-like fluorescent probe DS was designed and synthesized. The unique coupling systems of FRET and ICT effects were designed for DS, which was demonstrated to be capable of detecting aluminum ion through the FRET effect, changing the fluorescence of the solution from green to bright blue (55 nm blue-shift) with good selectivity and fast response, and detecting Al3+ over a wide pH range. The recognition mechanism was determined based on spectral characterization, in the sense that the coordination of Al3+ with the probe DS molecule turned on the intramolecular FRET and ICT processes. ESP analysis and DFT calculations validated the binding sites and fluorescence recognition mechanism. Finally, good results have been achieved in practical applications. The test paper experiment confirmed that DS can be prepared into portable Al3+ test paper, the fluorescence imaging experiment of mung bean sprouts showed that DS can be used for the fluorescence imaging of Al3+ in plants, and the environmental water samples test proved that various ions in the actual water samples hardly interfere with the identification of Al3+, and it is expected to be applied in the environmental testing and other fields.

La Y., Du M., Gan L., Zhang Y., Sun Y., Dong W.

A novel bis(salamo)-type sensor FT for fluorescence-colorimetric recognition of Fe3+/Cu2+ has been created, which revealed significant fluorescent performance and colorimetric sensing ability for Cu2+ and Fe3+ ions, superior to other related competitive metal ions. Interestingly, the binding of the FT probe with Cu2+ ions manifested an instant color change from colorless to red in sunlight, which is detectable by the naked-eye, and a fluorescence turn-off response under UV light for Fe3+ and Cu2+. The results demonstrated that the probe exhibits better sensitivity, greater affinity and lower limit of detection leading to quick response time in an aquo-organic medium. The excited state property of the FT probe and in the presence of Cu2+/Fe3+ was evaluated on the basis of DFT & TD-DFT results. Furthermore, test strips have been provided for convenient monitoring of Cu2+ and Fe3+ ions by naked eye and fluorescence method.

Kaur M., Janaagal A., Balsukuri N., Gupta I.

Aza-boron-dipyrromethenes (Aza-BODIPYs) are a class of dyes that display absorption and emission covering visible to NIR region. They can show NIR emission in the 700–1700 nm range and have diverse applications in biology, metal sensing and optical devices. Aza-BODIPYs have got attention for their superior spectral performances and applications in biology and material science. These dyes can be applied to fluorescence imaging, photodynamic/photothermal therapy, optoelectronics, etc. The aim of this review is to provide a comprehensive overview of streamlined development in the area of aza-BODIPY dyes and their applications in different areas. Firstly, general synthetic methodologies for the preparation of aza-BODIPYs are discussed. In the subsequent sections, the overview of tetra aryl, conformationally rigid and ring fused aza-BODIPYs, pyrrolopyrrole and extended aza-BODIPYs is presented. Later, sections describe the various applications of aza-BODIPYs in different areas such as: metal sensing, anion sensing, pH detectors, detection of biological analytes and energy transferring cassettes. The biological applications of aza-BODIPYs in fluorescence and photoacoustic imaging probes, as PDT and PTT agents, drug delivery systems are also discussed. Undoubtedly, it will be a one-stop solution for the science community to look for every structural aspect and application published from the year 2002 till May 2023.

La Y., Yan Y., Li X., Zhang Y., Sun Y., Dong W.

A novel Salamo-Salen-Salamo hybrid Mg(II) complex (sensor MT) was well-designed and synthesized for selective sensing of H2PO4ˉ ions through ICT and CHEF effects and via displacement pathways in DMSO/H2O (9:1, v/v) medium. The sensor MT exhibited a bright blue fluorescence signal (470 nm) that is quenched upon encountering H2PO4ˉ ions in a short time. The simplicity and specificity of the recognition process make it an ideal fluorescent probe for detecting H2PO4ˉ in test strip, Zebrafish, and bean sprout. Theoretical studies using UV–vis spectroscopy, HR-MS, 1H NMR titration, and theory calculations (DFT & TD-DFT) provided a better understanding of the sensing mechanisms and binding modes of the sensor MT and H2PO4ˉ. This new recognition strategy may open up new avenues for further applications in vitro, in vivo, and in plants.

Zheng Y., Ding Y., Chai Z., Wei Y., Wang L., Dong W., Ding Y.

In this work, we successfully designed and synthesized a methoxydisubstituted bis(salamo)-type fluorescent chemical sensor BS, which can be applied as a highly sensitive and selective fluorescence probe for HCO3- and CO32- detection. The LODs of HCO3- and CO32- were experimentally calculated to be 5.4068 × 10-8 M and 4.4517 × 10-8 M, respectively. After relevant experiments, the sensing mechanism was investigated. Moreover, the application of the sensor in practice is explored, and the sensor BS can be loaded on portable test strips for ion detection. In the field of ion detection, salamo-like chemical sensors have been less studied compared to other sensor molecules, especially for the recognition and detection of anions. Therefore, this study will to some extent contribute to expanding the application of salamo-like compounds.

Makarov D.M., Lukanov M.M., Rusanov A.I., Mamardashvili N.Z., Ksenofontov A.A.

The utilization of machine learning techniques for investigating chemical reactions is both sought after and challenging. While there are now many high-quality paid and free tools available for planning retrosynthesis, predicting the yield of different reaction types has received less attention, even though it is a crucial parameter for improving the synthesis process. This article aims to contribute to the application of machine learning in forecasting the yield of pyrrole and dipyrromethane condensation reactions with aldehydes. To achieve this, we trained a random forest model with an extended connectivity fingerprint on over 1200 such reactions, resulting in an MAE of 9.6 % and R2 of 0.63. To make it easier for users, we created the web application ChemPredictor (http://chem-predictor.isc-ras.ru/reaction/yield/) that allows users to input only the reaction components and temperature to predict the yield of these reactions.

Wang J., Gong Q., Jiao L., Hao E.

Photodynamic therapy (PDT) is a promising therapeutic approach for anticancer and antibacterial treatment via photoinduced reactive oxygen species (ROS) generation. Photosensitizer, the most important element of PDT, plays a decisive role in PDT treatment. BODIPY dyes, as a class of well-developed fluorescent dyes, have emerged as a new class of PDT agents over the past decade owing to their versatile and remarkable properties including high molar extinction coefficients and singlet-to-triplet intersystem crossing efficiencies, tunable absorption and emission wavelengths, good ROS-generation ability, excellent photo- and chemical- stability, and easy functionalization. Several chemical approaches have been applied to tune BODIPY fluorophores into triplet photosensitizers via converting the typical fluorescence decay into a non-radiative intersystem crossing to the triplet state. However, the poor water solubility, low tumor selectivity and limited biocompatibility still hamper their biological application. Supramolecular assembly strategies have provided a promising avenue to overcome current problems of BODIPY-based molecular photosensitizers in photodynamic anticancer and antibacterial therapy. So far, numerous types of self-assembled nano-platforms have been established for construction of BODIPY-assembled supramolecular photosensitizers. This review presents the main molecular design approaches for constructing BODIPY-based photosensitizers and systematically summarizes the research progress of BODIPY-assembled supramolecular photosensitizers for PDT treatment to provide meaningful guidance for developing highly efficient BODIPY-based photosensitizers suitable for their clinical translation and application.

Yue L., Ai Y., Liu Q., Mao L., Ding H., Fan C., Liu G., Pu S.

A series of fluorometric sensors of Zn2+ have been synthesized due to the significant function of Zn2+ in the human body and environment. However, most of probes reported for detecting Zn2+ have high detection limit or low sensitivity. In this paper, an original Zn2+ sensor, namely 1o, was synthesized by diarylethene and 2-aminobenzamide. When Zn2+ was added, the fluorescence intensity of 1o increased by 11 times within 10 s, along with a fluorescence color change from dark to bright blue, and the detection limit (LOD) was calculated to be 0.329 μM. According to Job’s plot curves, the binding mode of 1o and Zn2+ was measured as 1:1, which was further proved by 1H NMR spectra, HRMS and FT-IR spectra. The logic circuit was designed to take advantage of the fact that the fluorescence intensity of 1o can be controlled by Zn2+, EDTA, UV and Vis. In addition, Zn2+ in actual water samples were tested, in which the recovery rate of Zn2+ was between 96.5% and 109%. Furthermore, 1o was successfully made into a fluorescent test strip, which could be used to detect Zn2+ in the environment economically and conveniently.

Mondal T., Biswas S., Mane M.V., Panja S.S.

In this work, we introduced a simple aggregation-induced emission enhancement (AIEE) sensor (PHCS) which can selectively detect and discriminate three environmentally and biologically imperative heavy metal ions (Cu2+, Co2+ and Hg2+) and a hazard class 1 categorized nitro-explosive picric acid (PA) in differential media. By virtue of its weak fluorescence attributes in pure organic medium owing to the synergistic operation of multiple photophysical quenching mechanisms, the molecular probe showcased highly selective ‘TURN ON’ fluorogenic response towards hazardous Hg2+ with a limit of detection (LOD) as low as 97 nM. Comprehensive investigation of binding mechanism throws light on the cumulative effect of probe-metal complexation induced chelation enhanced fluorescence (CHEF) effect and subsequent AIEE activation within the formed probe-metal adducts. Noteworthily, the probe (PHCS) can be readily used in real water samples for the quantitative determination of Hg2+ in a wide concentration range. In addition, the probe displayed modest colorimetric recognition performances to selectively detect and discriminate two essential heavy metal ions (Cu2+ and Co2+) with a LOD of 96 nM and 65 nM for Cu2+ and Co2+ respectively, in semi-aqueous medium. Intriguingly, based on high photoluminescence efficiency, the AIEE active nano-aggregated PHCS displayed a remarkable propensity to be used as a selective and ultra-sensitive ‘TURN-OFF’ fluorogenic chemosensor towards PA with LOD of 34.4 ppb in aqueous medium. Finally, we specifically shed light on the interaction of PHCS hydrosol towards PA using some unprecedented techniques, which helped uncover new photophysical insights of probe-explosive molecule interaction. We shed light on novel photophysical insights toward unique multifunctional sensory aptitude of a simple aggregation-induced emission enhancement active organic functional molecule in differential media, enabling ultra-sensitive discriminative detection of toxic heavy metal ions and explosive molecule simultaneously.

Chen Y., Zheng S., Kim M.H., Chen X., Yoon J.

Metal ions are of significance in various pathological and physiological processes. As such, it is crucial to monitor their levels in organisms. Two-photon (TP) and near-infrared (NIR) fluorescence imaging has been utilized to monitor metal ions because of minimal background interference, deeper tissue depth penetration, lower tissue self-absorption, and reduced photodamage. In this review, we briefly summarize recent progress from 2020 to 2022 of TP/NIR organic fluorescent probes and inorganic sensors in the detection of metal ions. Additionally, we present an outlook for the development of TP/NIR probes for bio-imaging, diagnosis of diseases, imaging-guided therapy, and activatable phototherapy.

Yarullin D.N., Zavalishin M.N., Gamov G.A., Lukanov M.M., Ksenofontov A.A., Bumagina N.A., Antina E.V.

This review presents an analysis of different algorithms for predicting the sensory ability of organic compounds towards metal ions based on their chemical formula. A database of chemosensors containing information on various classes of suitable compounds, including dipyrromethenes, BODIPY, Schiff bases, hydrazones, fluorescein, rhodamine, phenanthroline, coumarin, naphthalimide derivatives, and others (a total of 965 molecules) has been compiled. Additionally, a freely available software has been developed for predicting the sensing ability of chemical compounds, which can be accessed through a Telegram bot. This tool aims to assist researchers in their search for new chemosensors.

Yan L., Lu D., Yang H., Wu X.

Zinc ions (Zn2+) and cadmium ions (Cd2+) are widely present in our production and life, which are closely related to human health and environmental protection. Hence, it is essential to detect their concentrations. Herein, we developed a convenient and reliable small-molecule fluorescent probe based on Schiff base of dicyanisophorone and 2-hydrazinopyridine. This probe can be able to selectively detect Zn2+ and Cd2+, showing the advantages of near-infrared emission (the maximum emission wavelength: 668 nm), good selectivity, high sensitivity (the detection limits: 0.21 µM and 0.31 µM, respectively) and rapid response (15 s). It has excellent potential for rapid testing and visual tracking of Zn2+ and Cd2+ in aqueous solution and living cells.

Cheng H., Cao X., Zhang S., Zhang K., Cheng Y., Wang J., Zhao J., Zhou L., Liang X., Yoon J.

The outline of the review is as follows. In Section 2, the synthesis and regulatory strategies for BODIPY are summarized, and inspiring cutting-edge work in post-functionalization strategies is highlighted. Section 3 gives a brief overview of assembly model of BODIPY. In this section, we introduce BODIPY as a promising building block for the formation of single- and multi-component self-assembled systems, including nanostructures suitable for aqueous environments, thereby showing the great development potential of supramolecular assembly in biomedicine applications. Section 4 describes the frontier progress of BODIPY in biomedical applications. This section reviews examples of the frontiers of biomedical applications of BODIPY-containing smart materials. It mainly involves the application of materials based on BODIPY building blocks and their assemblies in fluorescence bioimaging, PAI, disease treatment including PDT, PTT and immunotherapy. In Section 5, not only the current status of the BODIPY family in the biomedical field but also the challenges worth considering are summarized. At the same time, it also provides insights into the future development prospects of biomedically applicable BODIPY. This article is protected by copyright. All rights reserved.

Xu F., Zhang D., Lu Q., Zhang R., Xia J.

According to the assumption that the formation of C-Pd bond becomes a cyclopalladated complex (CPC), we designed and synthesized two C-N-N pincer ligands of BODIPY appended 2,2'-bipyridine derivatives (BP and BPB). It has been confirmed that the C-Pd bond does exist and plays a crucial role in "on-off" fluorescence behavior. Based on it, a coordination-induced fluorescence quenching sensor for Pd2+ was constructed. The results indicated that BP possessed high sensitivity and specificity for Pd2+ in solution. The limit of detection (LOD) of BP is determined to be 0.97 nM within a linear range between 1.0 and 50.0 nM, meanwhile, the platinum-group ions demonstrate no interference. The bio-imaging application of BP was investigated and it exhibited a promising vitro test for fluorescent imaging of Pd2+ ions in MCF-7 cells. Meanwhile, BPB coated sensor label for Pd2+ was set up. The visible color variation was displayed under UV light with increasing concentrations of Pd2+. Briefly speaking, fluorescence probes of BP and BPB offer new approaches for Pd2+ detection in a lab and on-site test, as well as the vivo imaging. Then, with the aid of (TD)DFT calculation, the internal reason for the optical difference between the two ligands was disclosed. This concept of CPC containing a Pd-C covalent bond provides a promising perspective of coordination fluorescence sensors.

Chen X., Niu W., Yuan Q., Zhang Y., Gao X., Su D.

Zn 2+ is one of the most critical micronutrients involved in embryonic development and growth. In situ tracking of the metabolic distribution of Zn 2+ during embryogenesis can help to understand its role. However, the lack of practical fluorescence imaging tools hinders the dynamic tracking of Zn 2+ changes and distribution in vivo . Here, we report a fluorogenic sensor BDA-1 based on BODIPY fluorophore, which can continuously monitor the changes and distribution of Zn 2+ and achieve fluorescence mapping of labile Zn 2+ in different organs during zebrafish embryonic development. The sensor BDA-1 itself exists as a tautomer and exhibits non-fluorescence due to the photo-induced electron transfer (PeT) process, while after specific binding to Zn 2+ , the product no longer exists as a tautomer and the fluorescence is significantly enhanced. The reversible behavior of fluorescence can be demonstrated in living cells and zebrafish. Furthermore, BDA-1 successfully mapped the distribution and changes of Zn 2+ at key stages of embryonic development. The sensor is expected to serve as a powerful tool to study Zn 2+ -related biological processes and promote the understanding of Zn 2+ functions in the course of embryonic development. • A high-performance off-on fluorogenic sensor BDA-1 for Zn 2+ has been reported. • BDA-1 showed rapid response, high specificity and sensitivity for detection of Zn 2+ . • BDA-1 could achieve reversibility for Zn 2+ in vitro , in cells and larval zebrafish. • The fluorescence mapping of Zn 2+ during zebrafish embryogenesis was exhibited.