[Study on two-photon induced fluorescence of newly synthesized chromophore BECVN and BMABN].

One-photon fluorescence(OPF) and two-photon fluorescence (TPF) of two chromophores 1,4-bis(9-ethyl-vinyl carbazole) naphthalene (abbreviated as BECVN) and 1,4-bis(4-N, N-methylamino styryl) naphthalene (abbreviated as BMABN) were resported. Strong emission at 492-541 nm and at 500-556 nm, respectively, were obtained under the excitation of -370 nm (Xe lamp) and of 730-800 nm femto-second laser pulses, respectively. Although the relative fluorescence quantum yield (phi(f)) of BECVN is as high as 7.4 times that of BMABN, the latter possesses higher TPF intensity and larger two-photon absorption (TPA) cross-section, suggesting that BMABN containing naphthalene as pi-center end-capped with N,N-methylamino styryl group exhibits more effective two-photon process. Lippert equation showed that the difference of dipole momnet (deltamu(ge)) between the ground state and the excited state for BECVN is nearly twice that for BMABN, conforming to that the deltamu(ge) value is not the key for the enhancement of two-photon absorption cross-section.

Triaryl boron-based A-pi-A vs triaryl nitrogen-based D-pi-D quadrupolar compounds for single- and two-photon excited fluorescence.

Three new A-pi-A-type compounds with trivalent boron, protected by two mesityl groups, as electron acceptor have been synthesized and investigated together with their two diphenylamino-ended D-pi-D analogues. These boranes exhibit large two-photon absorption cross sections and high fluorescence quantum yields.