Selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is one of the key reactions for producing chemical commodities from biomass and their derivatives. The challenge for this reaction is to develop an efficient catalytic process that can be conducted under mild conditions (room temperature and atmospheric pressure, using oxygen molecules in air as the oxidant) and a recyclable catalyst. Herein we report a photocatalyst of cobalt thioporphyrazine (CoPz) dispersed on g-CN (abbreviated as CoPz/g-CN), which exhibits excellent catalytic activity toward the selective oxidation of HMF into FDCA under simulated sunlight using oxygen molecules in air as a benign oxidant. For example, an FDCA yield of 96.1% in an aqueous solution at pH = 9.18 is achieved at ambient temperature and air pressure. At lower pH (4.01), the product generated is 2,5-diformylfuran. Hence, it is possible to control the reaction outcome by control of the pH of the reaction system. g-CN itself is not a suitable catalyst for the selective oxidation because under the experimental conditions g-CN generates hydroxyl radicals that initiate processes that oxidize HMF directly to CO and HO. CoPz on the other hand activates O to give singlet oxygen (O), which more controllably oxidizes HMF to FDCA albeit at a more moderate yield (36.2%). The strong interaction between the CoPz and g-CN in the CoPz/g-CN catalyst is experimentally evidenced, which not only improves accessibility of the CoPz sites and makes the catalyst recyclable but also disables the hydroxyl radical generation by g-CN and promotes O generation on the CoPz sites, significantly enhancing the catalytic performance. This study demonstrates the potential for efficient non-noble metal photocatalysts for organic transformations driven by sunlight.

A platinum 2,2 0 -bipyridine complex (1) bearing 2-(benzothiazol-2 0 -yl)-9,9-diethyl-7-ethynylfluorene ligands was synthesized and characterized. Its photophysical properties and nonlinear absorption characteristics were systematically investigated by UV-vis absorption, emission, and transient difference absorption spectroscopy, as well as Z-scan and nonlinear transmission techniques. Complex 1 exhibits a strong structureless 1 π,π* absorption band at 374 nm and a broad, weak metalto-ligand charge transfer ( 1 MLCT) transition in the visible region in CH 2 Cl 2 solution. It emits at approximately 565 nm with vibronic structures at room temperature in polar solvents, attributed to the acetylide ligand 3 π,π* excited state. In low-polarity solvents such as hexane and toluene, the emission band becomes structureless and red-shifted, which is assigned to the 3 MLCT state. The emission spectrum becomes more structured and slightly blue-shifted at 77 K in butyronitrile glassy matrix. In femtosecond and nanosecond transient absorption measurements, 1 exhibits both singlet and triplet excited-state absorption from 450 to 800 nm, which are tentatively attributed to the 1 π,π*/ 1 MLCT and 3 π,π*/ 3 MLCT, respectively. Z scan experiments were carried out using nanosecond and picosecond pulses at 532 nm, and picosecond pulses at a variety of other wavelengths in the visible and near-IR, and the experimental data were fitted by a five-level model using the excited-state lifetimes and estimated cross-section values from the photophysical study. In this way, values were obtained for the first and second singlet excited-state absorption cross sections and the triplet excitedstate absorption cross section throughout the visible and near-IR and for the two-photon absorption (TPA) cross section in the near-IR region. Our results demonstrate that 1 possesses extremely large ratios of the excited-state absorption cross sections to the ground-state absorption in the visible spectral region and, compared to the other two-photon absorbing platinum complexes, the largest two-photon absorption cross sections in the near-IR region. This makes complex 1 a very promising candidate for photonic devices that require large and broadband nonlinear absorption. Reverse saturable absorption of 1 in CH 2 Cl 2 solution at 532 nm for a nanosecond laser pulse was demonstrated. A remarkable transmission decrease was observed when the incident fluence increased.

A test paper for high-selectivity detecting fluoride ion in natural aqueous environments without any spectroscopic instrumentation was achieved by using Ru-bipy based quinonehydrazone as a chromo- and fluorogenic hybrid chemosensor.

A family of thiophene-based metal-organic frameworks (MOFs), [Zn(L)(BBI)·(HO)] (1) (BBI = 1,1'-(1,4-butanediyl)bis(imidazole)) and [Cd(L)(TPOM)]·xS (2) (TPOM = tetrakis(4-pyridyloxy-methylene) methane, S represents noncoordinated solvent molecules) was constructed by employing a new linear thiophene-functionalized dicarboxylic acid (benzo-(1,2;4,5)-bis(thiophene-2'-carboxylic acid, HL) to assemble with d ions in the presence of a flexible ancillary ligand under solvothermal conditions, which exhibit diverse structures. Most strikingly, both compounds 1 and 2 could be efficient luminescent sensory materials that are highly selective and sensitive to environmental contaminants, especially for Hg(II), Cu(II), Cr(VI), and salicylaldehyde, and yet remain unaffected by other molecules that may coexit. Furthermore, this is the first report on MOF-based sensors capable of recyclable detection of Hg(II), Cr(VI), and salicylaldehyde so far. The luminescent sensing mechanism was studied in detail as well. In addition, compound 2 is one of the rare examples of high-performance MOFs trapping 2,4-dichlorophenol from the wasted methanol solution.