N,O-bidentate ligands-based salicylic spiroborates: A bright frontier of bioimaging

A new series of salicylic spiroborate complexes (SSBs) based on N,O-bidentate 2-( tert -cycloalkylamino)-5-(3-(arylamino)acryloyl)thiophene-3-carbonitriles (NO-SSBs) was obtained and characterized. The optical properties of these compounds were studied and compared with those of analogous BF 2 -based complexes. The geometries and electronic structures of the NO-SSBs in the ground and excited states, especially their key N–B–O link, were revealed using quantum chemical calculations and compared with the experimental data and photophysical characteristics. Hydrolytic dissociation and photodissociation were considered, and the effects of the NO-SSB structure and nature of the solvent on these reactions were established. Biological investigations elucidated the NO-SSBs ability to penetrate living and fixed cells and selectively accumulate in the endoplasmic reticulum (ER) and Golgi complex. Comparison of the NO-SSBs’ characteristics with those of a commercial dye demonstrated the superiority of their properties and prospects for application in the bio-visualization of the ER and Golgi complex. • A series of new salicylic tetracoordinate NO-spiroborates was prepared. • NO-SSBs exhibited intensive absorption in the visible region and bright green-yellow fluorescence. • Theoretical calculations demonstrated the specific of geometry and electronic structure NO-SSBs in GS and ESs. • NO-SSBs have shown superior behavior in biological systems compared to commercial dye.