The large conjugated system and the d orbitals of metallic phthalocyanines (MPcs) are easily triggered by solvent molecules and light to cause variations in photo-physical and photo-chemical properties. To clarify the novel properties of photo-excited MPcs in solvents, the steady/transient state spectral data were collected to investigate four MPc templates, including FePc, ZnPc, CoPc and AlClPc. The Q bands of FePc and CoPc were prone to redshift, while the peaks of ZnPc and AlClPc tended to blueshift in various solvents compared with that in DMSO. With xenon lamp irradiation, the characteristic absorption peak intensity of FePc and ZnPc in DMSO decreased gradually and then increased after being subjected to dark condition. The transient absorption spectra and kinetic data illustrated that photo-excited FePc and CoPc produced relatively short lifetime transient intermediates. The positive absorption at 650 nm in the Q bands of FePc and CoPc could be assigned to the d–π* electron transition in transient intermediates with unpaired d-orbital electron in the open shell configuration of Fe2+ and Co2+. The above studies were of great significance for the application of solvent-triggered and photo-induced novel properties of MPcs.
Xinyue Sun,Junjie Ni,Yuhan Lou,Peng Zhao,Yanyan Yu,Yilin Li,Qi Tang,Haipeng Yu,Yongzhuang Liu
Solvents with integrated functions enable directional lignin valorization for producing value-added chemicals or lignin polyols. In this study, a solvent-triggered directional lignin valorization process was developed based on the design of a biphasic deep eutectic solvent/dichloromethane (DES/DCM) system. The designed solvents exhibit a combined feature of chemical stabilization from ethylene glycol-based-DES and physical stabilization from a biphasic system. By establishing the DES/DCM, lignin was effectively functionalized into lignin polyols with high yield. Furthermore, by implementing a simple recycling procedure of the DCM phase, the reaction pathway was switched, leading to depolymerization and stabilization of the stabilized lignin polyols. This process resulted in an almost threefold increase in monomeric acetal yields. The effect of biphasic DES on functionalization or switched depolymerization of lignin was confirmed through model compound studies. Our findings demonstrate a directional lignin valorization route using the designed biphasic DES system, which offers potential applications in the production of value-added aromatic chemicals or potential intermediates for polymers.
Liu Chun-Yu,Yuan Shang-Fu,Wang Song,Guan Zong-Jie,Jiang De-en,Wang Quan-Ming
Copper hydrides are important hydrogenation catalysts, but their poor stability hinders the practical applications. Ligand engineering is an effective strategy to tackle this issue. An amidinate ligand, N,N′-Di(5-trifluoromethyl-2-pyridyl)formamidinate (Tf-dpf) with four N-donors has been applied as a protecting agent in the synthesis of stable copper hydride clusters: Cu 11 H 3 (Tf-dpf) 6 (OAc) 2 ( Cu 11 ) with three interfacial μ 5 -H and [Cu 12 H 3 (Tf-dpf) 6 (OAc) 2 ]·OAc ( Cu 12 ) with three interstitial μ 6 -H. A solvent-triggered reversible interconversion between Cu 11 and Cu 12 has been observed thanks to the flexibility of Tf-dpf. Cu 11 shows high activity in the reduction of 4-nitrophenol to 4-aminophenol, while Cu 12 displays very low activity. Deuteration experiments prove that the type of hydride is the key in dictating the catalytic activity, for the interfacial μ 5 -H species in Cu 11 are involved in the catalytic cycle whereas the interstitial μ 6 -H species in Cu 12 are not. This work highlights the role of hydrides with regard to catalytic hydrogenation activity.
危险品化学品经营许可证（带存储）