Solvatochromic Behavior of 2,7-Disubstituted Sila- and Germafluorenes

Push–pull dyes exhibit intramolecular charge transfer behavior, which due to changes in the dipole moment upon excitation, is origin of their sensitivity environment. Such compounds are interest as probes for bioimaging and biosensors monitor cellular dynamics molecular interactions. Desirable biological absorb visible region, have high extinction coefficients, quantum yield excellent photostability. Fluorophores with scaffolding that can be used tune optimize solvatochromic behavior particular interest. Here, we investigate environmental a small library highly fluorescent 2,7-disubstituted sila- germafluorenes. Density functional theory (DFT) calculations show occurs from alkyne core out 2,7-substitutents 3,6-methoxy substituents, hallmark push–pull behavior. They HOMO–LUMO energy gaps about 3 eV desirable moments ranging 2 9 D. These Stokes shifts various solvents (25 102 nm). Interestingly, silafluorene benzaldehyde substituent exhibits competitive With ability properties via 2,7-substituent, these disubstituted germafluorenes potential probes.