Abstract
Nitric oxide (NO) is a ubiquitous signaling molecule in a variety of
physiological and pathological process in living organisms. A two-photon
probe, i.e., 2-acetyl-6-dialkylaminonaphthalene as the reporter and an
o-diaminobenzene as the reaction site for NO, linked by prolinamide
(ANO1), has been synthesized. Based on the experimental study, five
other two-photon probes have been designed by substituting the
naphthalene fluorophore in ANO1 with the luciferin analogue (ANO2),
pyrene (substitution at 1,6-position, ANO3, and 2,7-position, ANO3’),
fluorene (ANO4), and boron-dipyrromethene (ANO5) units. DFT/TDDFT
studies have been conducted on both experimental two-photon probe ANO1
and designed ANOn (n=2–5). Our results indicated that for designed
probes, both absorption and emission spectra show red shifts compared
with ANO1. The one- and two-photon absorption band positions as well as
the emission wavelength do have no significant change for each probe
before and after reaction with NO. However, the fluorescence intensities
are enhanced after reaction with NO. ANO3 and ANO4 have large two-photon
absorption cross sections. Furthermore, analysis of molecular orbitals
is exhibited to interpret the photoinduced electron transfer mechanism
between the donor and acceptor.