BTD-1

In the present study, a series of non-chelated BTD (2,1,3-benzothiadiazole)-bridged diruthenium(II) ([{(CH3CN)(acac)2RuII}2(μ-BTD)] 1, [{CH3CN(acac)2RuII}(μ-BTD){RuII(acac)2(η1-N-BTD)}] 2, [{(η1-N-BTD)(acac)2RuII}2(μ-BTD)] 3), and triruthenium ([{(acac)2RuII}3(μ-BTD)2(η1-N-BTD)2] 4) complexes with varying ratios of η1-N and μ-bis-η1-N,η1-N modes of BTD were studied. Complexes 1-4 (S = 0) were obtained via the one-pot reaction of electron-rich Ru(acac)2(CH3CN)2 and electron-deficient BTD in refluxing acetone. The relatively low Ru(II)/Ru(III) potential of 1-4 (0.08-0.44 V versus SCE) further facilitated the isolation of the corresponding mixed valent RuIIRuIII (S = 1/2) and RuIIRuIIRuIII (S = 1/2)/RuIIRuIIIRuIII (S = 1) forms [1]ClO4-[3]ClO4 and [4]ClO4/[4](ClO4)2, respectively. The single-crystal X-ray structures of the representative mixed valent [1]ClO4 and [3]ClO4 established (i) Ru⋯Ru distances of 6.227 Å and 6.256 Å (molecule A)/6.184 Å (molecule B), respectively, (ii) a significant variation of the N-S distance of BTD in [3]ClO4 as a function of its binding mode μ versus η1 and (iii) similar Ru-N (μ-BTD) distances in each case corresponding to a valence delocalised situation. The mixed valent diruthenium (1+-3+) and triruthenium (4+/42+) complexes exhibited metal-based anisotropic electron paramagnetic resonance (EPR) and moderately intense low-energy intervalence charge-transfer (IVCT) transitions in the near-infrared region of 1730-1890 nm. Analysis of the IVCT band using the Hush treatment revealed a valence delocalised class III mixed valent state with the electronic coupling Vab of ≈2640-2890 cm-1, as also corroborated by the Kc values of 105-108, solvent independency of the IVCT band and uniform spin distribution between the metal ions in the singly occupied state(s). Furthermore, the involvement of the BTD (η1 and μ)-based orbitals in the reduction processes was evident by its free radical EPR feature.

The application of TiO2-based photocatalysts in air pollution control has attracted much attention thanks to their advantageous green and sustainable performance. However, how to improve the degradation efficiency under visible light is still challenging. Herein, we report a ternary three-dimensional "PIZZA"-like Bi2MoO6-TiO2/diatomite (BTD) composite with high-efficient mineralization and recycling performance towards gaseous formaldehyde (HCHO) under visible light. The high-efficient adsorption-photocatalysis collaborative system with intimate interface combination is successfully established among Bi2MoO6 (BMO), TiO2 and diatomite. The HCHO mineralization rate constant of BTD-1:2 composite is up to around 4.03 times and 2.18 times higher than those of bare BMO and binary Bi2MoO6-TiO2 composite, respectively. It is indicated that the introduction of diatomite increases active sites and plays the vital role in the improvement of photocatalysis. In addition, the photogenerated holes (h+) and hydroxyl radical (OH) are proved to be the main active species for HCHO mineralization. Furthermore, there is a competitive adsorption relationship between water (H2O) molecules and HCHO molecules, and both H2O molecules and oxygen (O2) molecules participated in the reaction of HCHO mineralization based on in-situ DRIFTs spectra analysis. Our work would give a new perspective on gaseous HCHO purification.

We report synthesis, crystal structure, and photophysical properties of novel 1,3-phosphinoamines based on 4-amino-2,1,3-benzothiadiazole (NH2-btd): Ph2PCH(Ph)NH-btd (1) and Ph2P(E)CH(Ph)NH-btd, (E = O (2α and 2β·thf), S (3), Se (4)). Chalcogenides 2-4 exhibit bright emissions with a major band at 519-536 nm and a minor band at 840 nm. According to TD-DFT calculations, the first band is attributed to fluorescence, while the second band corresponds to phosphorescence. In the solid state, room temperature quantum yield reaches 93% in the case of the sulphide. The compounds under study feature effects of the molecular environment on the luminescent properties, which manifest themselves in fluorosolvatochromism as well as in a luminescent response to changes in crystal packing and in contributions to aggregation effects. Specifically, transformation of solid 2β·thf to solvate-free 2β either by aging or by grinding causes crystal packing changes, and, as a result, a hypsochromic shift of the emission band. Polystyrene films doped with 2 reveal a bathochromic shift upon increasing the mass fraction from 0.2 to 3.3%, which is caused by molecular aggregation effects.