Computational design of zinc ion responsive two photon fluorescent probes with conjugated multi structures
AbstractA series of conjugated multi structured fluorescent probe molecules based on a salen ligand were designed and investigated in dimethyl sulfoxide solvent using a quantum chemical method. The results indicate that the one photon absorption and fluorescence emission spectra (lO and lEM) of these molecules generally show redshifts (of 23.1 74.5 and 22.7 116.6 nm, respectively) upon the coordination of the molecules to Zn2+ Large Stokes shifts (1511.2 11744.1 cm 1) were found for the molecules, meaning that interference between lO and lEM can be avoided for these molecules. The two photon absorption spectra of the molecules usually present blueshifts, but the two photon absorption cross section (d) greatly increases (by 221.5 868.0 GM) upon the coordination of the molecules with Zn2+ Most of the molecules show strong two photon absorption peaks in the range 678.2 824.4 nm, i.e. in the near infrared region. In a word, the expanded p conjugated frameworks of these molecules lead to redshifted lO and lEM and enhanced d values. Moreover, (L phenyl) 2 and (L phenyl ethynyl)2 are the most suitable of the multi structured molecules examined in this work for use as two photon fluorescent probes for zinc ion detection in vivo. Graphical AbstractScheme of the calculated transition energies (E0k and E0n) and the transition dipole moments (M0k and Mkn) NTO 109, NTO 197 and NTO 228 of Zn(L phenyl ethynyl) Zn2(L phenyl ethynyl)2 and Zn3(L phenyl)3 for one photon absorption, respectively.
Journal of Molecular Modeling