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A multidentate ligand chromophore, combining rhodamine, triazole, and pyridine units, was identified and developed for the first time. Using triazole and pyridine rings as coordinating functional recognition groups, it was expected to selectively recognize Sn2+ to form some stable 5-member or 6-member rings with nitrogen and oxygen atoms. Under the optimized conditions, the ligand chromophore could selectively react with trace Sn2+ in CH3CN/H2O (99/1, v/v), accompanying with obvious changes in fluorescent spectrum, ultraviolet-visible spectrum and visual color. For fluorescent analysis, a turn-on fluorescence at 587 nm was found and increased linearly in the range of 1.2–6.2 × 10−7 mol L−1 Sn2+ from colorless to orange. For ultraviolet-visible one, a new absorption peak at 560 nm emerged with a linear range of 2.0–11.0 × 10−7 mol L−1 Sn2+ from colorless to pink. The action mechanism between the ligand chromophore and Sn2+ was confirmed basing on ultraviolet-visible titration, 1H NMR titration, Job's plot, binding constants and theoretical calculation in detail.

In this work, in order to solve the limitation of rhodamine B hydrazide (RBH) based water molecule detector (aggregation effect, poor optical stability, narrow detection range), a simple and effective method was studied. The specific design is as follows. Based on a simple thermodynamic controllable strategy, RBH is grafted onto a single layer graphene oxide (GO) via a covalent bond to prepare RBH functionlized graphene oxide (RBH-GO). The experimental results show that the resulting RBH-GO possesses very well monodispersion and hydrophilicity, particularly reduce the aggregation degree of alone RBH or GO owing to π-π stacking effect. Simultaneously, it is found that the prepared RBH-GO can detect water content in a very wide range (0.9–60 vol%, the volume percentage of water in the organic solvent) in organic solvent and food at room temperature 25 °C for production monitoring due to the strong synergistic effect between RBH and GO in resulting RBH-GO. The resulting RBH-GO not only possesses very well photostability, multiple repeated cycles and convenient application as a test paper, but also have been triumphantly put into the identification of H2O content in honey and salt specimens in practice for production quality control. The detection limit is as low as 0.21 vol%, and the correlation coefficient is 0.9997.

Broadening the absorption spectra of dyes is an effective way to increase the energy conversion efficiency in dye-sensitized solar cells. Here POSS-based hybrids with broad-band absorbing properties were successfully prepared by using octavinyl-polyhedral oligomeric silsesquioxane (OV-POSS) and three organic molecules with their absorption band in the range of UV, Vis and NIR via Heck reaction. The structure and property of the hybrids were well characterized by FTIR, 1 H NMR, UV-Vis-NIR and fluorescence spectra. It was found that the hybrids not only combined the absorbing bands of different dyes, but also prevented the aggregation of dye chromophores, resulting in an improvement in optical stability.

A novel multifunctional chemo-sensor (RHCS-NH2), incorporating Schiff base, rhodamine B hydrazide, hydrazine hydrate group into triazine, was successfully designed and synthesized. It was found that the RHCS-NH2 sensor displays immediate multi-response toward Ca2+ in CH3CN-H2O (v/v = 9/1, Tris-HCl pH 7.0) and Zn2+ in DMF-H2O (95/5, v/v). Under the optimized conditions, the linear range of identifing Ca2+ ions are from 0.01 to 10.0 μM in CH3CN-H2O (v/v = 9/1, Tris-HCl pH 7.0), 0.03–10.0 μM for Zn2+ ions in DMF-H2O (95/5, v/v), and the detection limit were measured to be 0.10 nM for Ca2+ and 0.14 nM for Zn2+, respectively. The reaction mechanism between RHCS-NH2 and metal ions was investigated in detail based on fluorescence titration, Job's plots and 1H NMR titration curve, ESI-MS measurement and theoretical calculation respectively. Simultaneously, 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assays and inverted fluorescence microscopy imaging also demonstrated that the probe has well cell membrane permeability and hypotoxicity, indicating its potential applicability in vitro.

To further investigate the dependence of optical limiting properties on molecular structures, especially the strong intermolecular influence, such as the influences of hydrogen bond, dipole–dipole interaction and their synergetic effect on optical limiting properties, three polar D–π–A conjugated quinoline-based heterocyclic azo derivatives (3a, 3b and 3c) with different hydrogen-bond recognition abilities were designed and synthesized. Their structures and properties were characterized and evaluated by infrared spectroscopy, thermogravimetric analysis, and ultraviolet–visible spectrometry. The strengthening mechanism of optical limiting property was investigated in detail based on theoretical calculation and experimental results of molecular assembly induced by synergetic effect of hydrogen bond and dipole–dipole interaction. The results indicate that the optical limiting properties of these polar D–π–A conjugated optical materials were significantly affected by molecular structure, strong intermolecular interaction and their synergetic enhancement effect.

Four novel triazole bridge-linked fluorene derivatives with different terminal push/pull substituted groups were designed and controlledly synthesized via click chemistry based on Huisgen 1,3-dipolar cycloaddition reaction in high yields. Their structures were characterized and evaluated by FTIR, 1H NMR, 13C NMR, MS and elemental analyses, respectively. The results show that these triazole bridge-linked fluorene optical materials are almost prepared quantificationally by click chemistry. The intramolecular charge transfer (ICT) in these triazole bridge-linked fluorene optical materials was investigated by molecular emission and absorption spectra, and further confirmed by cyclic voltammetry (CV) technology and theoretical simulation calculation. It is found that the intramolecular charge transfer is significantly affected by molecular structure. ICT emission, ICT/locally excited (LE) mixture emission and LE emission were achieved by changing the terminal group in triazole bridged conjugates.

A series of organic/inorganic molecular hybrid nonlinear optical materials were prepared by incorporating azobenzene nonlinear optical chromophores into nanosized, inorganic, polyhedral oligomeric silsesquioxane. Each of the hybrids was soluble in common solvents such as CHCl 3 , THF, toluene and C 2 H 4 Cl 2 , and exhibited good film-forming properties. Their structures and properties were characterized using FTIR, 1 H NMR, 13 C NMR, 29 Si NMR, UV, TGA, DSC and nonlinear optical analyses, respectively. All hybrid compounds displayed good optical limiting properties, large nonlinear optical response and high thermal stability. The optical limiting mechanism was investigated.

Three novel organic optical materials, 4′-( N , N -dihydroxyethylamino),4-(pyridine-4-vinyl)stilbene ( 8a ), N -((4- N , N -dihydroxyethylamino)benzylidene)-4-(pyridine-4-vinyl)aniline ( 8b ) and 4′-( N , N -dihydroxyethylamino),4-(pyridine-4-vinyl)azobenzene ( 8c ), were synthesized and characterized by FT-IR, UV, 1 H NMR and elementary analysis. Their optical properties were evaluated by optical limiting and nonlinear optical analyses. The results show that these compounds possess good optical limiting and large nonlinear optical properties, which are attributed to the long D-π-A conjugated electron structure of molecules, and the π-electron conjugated bridge structure affects the nonlinear optical and optical limiting properties of D-π-A conjugation compounds. The compound 8a with C C double bond as conjugation bridge shows better optical limiting property than compounds 8b and 8c with C N or N N double bond under the same linear transmittance, while compound 8c with N N double bond as conjugation bridge is superior in nonlinear optical properties to compounds 8a and 8b with C C or C N double bond as conjugation bridge.

Three conjugated molecules’, 4-phenylethynyl-4#-[N,N-diethylamino]azobenzene (3a), 4-phenylethynyl-4#-{[N-ethyl-N-(2hydroxyethyl)]amino}azobenzene (3b), and 4-phenylethynyl-4#-[N,N-di(2-hydroxyethyl)amino]azobenzene (3c), nonlinear optical properties were determined using Z-scan technique with 532 nm, 8 ns laser pulses. The results indicate that these compounds possess large nonlinear optical absorptions, which are attributed to the long p-conjugation structure owing to the substituent of phenylethynyl group. The nonlinearity increases with an increase in the number of hydroxyl group, due to the regular arrangement induced by the strong hydrogen bond interaction between hydroxyl groups of molecules. Their nonlinearity enhancement mechanism was studied by FT-IR spectroscopy. 2005 Elsevier Ltd. All rights reserved.