Study On Two-photon Fluorescence Dyes And Sensors Derived From Terephthalonitrile

The designs and syntheses of organic molecules with large two-photon absorption cross section (δ_tpa) and strong upconversion fluorescence are able to greatly promote the applications of TPFM in biological system, which is composed of single-molecule determinations, immunoassays, detection of single DNA Fragments, chemosensors and biological sensors, microchips in biochemical analyse, submicrometer capillary electrophoresis separation, and so on. Two-photon fluorescence molecules can avoid such drawbacks as photobleaching, photodamage, tissue autofluorescence, etc, which results from one-photon excitation. Moreover, TPFM possesses fixed target excitation, high transverse and lognitudinal resolutions, and low fluorescence loss. Two-photon imaging exhibits unparalleled strong points, and becomes a powerful tool for study on mechanisms of object activities, and its applications undoubtedly stimulate the developments of life science and medicine.A series of two-photon fluorescent dyes for D-A-D and A-A-A 2,5-dicyano-1,4-Bis(substituted styryl)benzene with double cyano groups were synthesized. The effects of their terminal substituted groups upon theirδ_tpa and solubilities were detailed studied, which suggests that terminal amino can remarkably increase molecular, fluorescence quantum yield, and large emission wavelength.Double cyano groups in the single aromatic ring are originally and covalently attached to the acceptor terminus for stilbene of D-π-A type, which (i) notably extends conjugation system of a molecule and enhancesδtpa and fluorescence quantum yield, and (ii) improves electron- accepting ability of acceptor terminus for a molecule to increase dipole moment of the excitation state, namely molecular charge transfer extent, and enlarges molecular multiple-frequency and two-photon absorption, and (iii) attenuates molecular symmetry to form center-asymmetry space group, and to ensure that a molecule possesses the excitation state dipole moments. At the same time, amino group is substituted into molecular another termini, and cooperatively interacts with cyano groups to make a molecule gain strong two-photon absorption.A series of D-π-A and A-π-A two-photon fluorescent dyes with double cyano groups derived from stilbene were synthesized. The effects of their terminal substituted groups upon theirδ_tpa, photophysical properties, and solubilities were detailed studied, which suggests that terminal amino can remarkably increase molecular , fluorescence quantum yield, and large emission wavelength.A number of D-π-A and D-A-D two-photon fluorescent sensors for metal cations with double cyano groups were synthesized. These sensors selectivities for metal ions, UV-Vis titration, one- and two-photon fluorescence titrations, andδ_tpa were studied. The results imply that these sensors can be used to detect some metal ions by means of two-photon fluorescence titration.Several D-π-A two-photon solvatochromic probes with double cyano groups derived from stilbene were synthesized. The influences of solvent polarities viscosities, and temperatures upon one- and two-photon fluorescence spectroscopies of these probes were systematically studied. Good linear relatives were revealed between the emission maxima wavenumbers of these probes and solvent polarity parameters.δ_tpa of these probes generally decrease upon the increases of solvent polarities. These solvatochromic probes can be capable of the detections for solvent polarities, viscosities and setting temperatures.