By virtue of a 3∶1 complementary coordination strategy,a chiral heteroleptic metal-organic cage that con-tains divergent functional units,Pd‑R(Zn),was precisely constructed via self-assembly of monodentate variationa...By virtue of a 3∶1 complementary coordination strategy,a chiral heteroleptic metal-organic cage that con-tains divergent functional units,Pd‑R(Zn),was precisely constructed via self-assembly of monodentate variational Zn-salen ligands RZn and NADH(reduced nicotinamide adenine dinucleotide)mimic modified tridentate ligands with square-planar Pd ions.UV-Vis and luminescence spectra experiments reveal that different anions could selec-tively interact with different sites of Zn-salen modified metal-organic cages to achieve the structural regulation of cage compound,by using the differentiated host-guest electrostatic interactions of counter ions with metal-organic hosts.Compared to other anions,the presence of chloride ions caused the most significant fluorescence emission enhancement of Pd‑R(Zn),meanwhile,the UV-Vis absorption band attributed to the salen aromatic backbone showed an absorption decrease,and the metal-to-ligand induced peak displayed a blue shift effect.Circular dichro-ism and ^(1)H NMR spectra further demonstrate that the introduction of chloride anions is beneficial to keeping a more rigid scaffold.展开更多
1-Tetralone, a useful synthetic intermediate in the manufacture of pharmaceuticals, agrochemicals and dyes, can be prepared by liquid phase catalytic oxidation of tetralin. Selective oxidation of tetralin to 1-tetralo...1-Tetralone, a useful synthetic intermediate in the manufacture of pharmaceuticals, agrochemicals and dyes, can be prepared by liquid phase catalytic oxidation of tetralin. Selective oxidation of tetralin to 1-tetralone is still a big challenge with low-temperature processes using environmentally friendly routes even after decades of research. Herein, we demonstrate room-temperature oxidation of tetralin to 1-tetralone over layered double hydroxide-hosted sulphonato-salen-nickel(II) complex, LDH-[Ni-salen]. The layered double hydroxide-hosted sulphonato-salen-nickel(II) compound was characterized by powder X-ray diffraction, Fourier transform infrared spectrometer (FTIR), UV-Visible diffuse reflectance spectra, scanning electron microscopy (SEM) and elemental analysis. The theoretical calculations of free sulphonato-salen-nickel(II) complex using Density Functional Theory/CAM-B3LYP at the 6-311++ G(d,p) level of theory were also used to determine the orientation of the Ni-salen compound within the layered structure. The immobilized compound, LDH-[Ni-salen] was found to be an effective reusable catalyst for the oxidation of tetralin to 1-tetralone using a combination of trimethylacetaldehyde and molecular oxygen (14.5 psi) and at 25°C. At 45.5% conversion, tetralin was converted to 1-tetralone with 77.2% selectivity at room temperature and atmospheric pressure after 24 h. The catalyst recycles test and hot filtration experiment showed that oxidation proceeded through Ni(II) sites in LDH-[Ni-salen]. The catalysts were reused several times without losing their catalytic activity and selectivity. The present results may provide a convenient strategy for the preparation of 1-tetralone using layered double hydroxide-based heterogeneous catalyst at ambient temperature for industrial application in near future.展开更多
Six novel chiral dinuclear Salen complexes[Cu 2 L 1 ·H 2 O(3a),Cu 2 L 2 (3b),Ni 2 L 1 ·2H 2 O(4a),Ni 2 L 2 (4b),Mn 2 Cl 2 L 1 ·H 2 O(5a),Mn 2 Cl 2 L 2 (5b)]have been synthesized(L 1 and L 2 are chiral d...Six novel chiral dinuclear Salen complexes[Cu 2 L 1 ·H 2 O(3a),Cu 2 L 2 (3b),Ni 2 L 1 ·2H 2 O(4a),Ni 2 L 2 (4b),Mn 2 Cl 2 L 1 ·H 2 O(5a),Mn 2 Cl 2 L 2 (5b)]have been synthesized(L 1 and L 2 are chiral dimeric Salen ligands with different chain length which were synthesized from(R,R) - diaminocyclohexane,salicylaldehyde,4,4 ’- (1,10 - decaneoxy)sali - cylaldehyde,4,4 ’- (1,6 - hexyloxy)salicylaldehyde).These compounds were charactered by elemental analysis,1 H NMR,FT - IR,UV - Vis and CD spectra.The FT - IR,UV - Vis and CD spectra were discussed and compared with those of monomeric ligand and complex in detail.It was found that the spectra properties of compounds of differ - ent chain length were almost alike,and the properties of dimeric and monomeric compound were similar too.Furthermore Cotton effect and Cotton split of CD spectra of these chiral compounds were explained by the exciton interaction theory.It seemed that the direction of Cotton split depend on the configuration of diaminohexane.(R,R) - diaminohexane determine the chirality of Salen compounds as negative,and the positive and negative compo - nent of Cotton split lie at higher and lower energy respectively.展开更多
文摘By virtue of a 3∶1 complementary coordination strategy,a chiral heteroleptic metal-organic cage that con-tains divergent functional units,Pd‑R(Zn),was precisely constructed via self-assembly of monodentate variational Zn-salen ligands RZn and NADH(reduced nicotinamide adenine dinucleotide)mimic modified tridentate ligands with square-planar Pd ions.UV-Vis and luminescence spectra experiments reveal that different anions could selec-tively interact with different sites of Zn-salen modified metal-organic cages to achieve the structural regulation of cage compound,by using the differentiated host-guest electrostatic interactions of counter ions with metal-organic hosts.Compared to other anions,the presence of chloride ions caused the most significant fluorescence emission enhancement of Pd‑R(Zn),meanwhile,the UV-Vis absorption band attributed to the salen aromatic backbone showed an absorption decrease,and the metal-to-ligand induced peak displayed a blue shift effect.Circular dichro-ism and ^(1)H NMR spectra further demonstrate that the introduction of chloride anions is beneficial to keeping a more rigid scaffold.
文摘1-Tetralone, a useful synthetic intermediate in the manufacture of pharmaceuticals, agrochemicals and dyes, can be prepared by liquid phase catalytic oxidation of tetralin. Selective oxidation of tetralin to 1-tetralone is still a big challenge with low-temperature processes using environmentally friendly routes even after decades of research. Herein, we demonstrate room-temperature oxidation of tetralin to 1-tetralone over layered double hydroxide-hosted sulphonato-salen-nickel(II) complex, LDH-[Ni-salen]. The layered double hydroxide-hosted sulphonato-salen-nickel(II) compound was characterized by powder X-ray diffraction, Fourier transform infrared spectrometer (FTIR), UV-Visible diffuse reflectance spectra, scanning electron microscopy (SEM) and elemental analysis. The theoretical calculations of free sulphonato-salen-nickel(II) complex using Density Functional Theory/CAM-B3LYP at the 6-311++ G(d,p) level of theory were also used to determine the orientation of the Ni-salen compound within the layered structure. The immobilized compound, LDH-[Ni-salen] was found to be an effective reusable catalyst for the oxidation of tetralin to 1-tetralone using a combination of trimethylacetaldehyde and molecular oxygen (14.5 psi) and at 25°C. At 45.5% conversion, tetralin was converted to 1-tetralone with 77.2% selectivity at room temperature and atmospheric pressure after 24 h. The catalyst recycles test and hot filtration experiment showed that oxidation proceeded through Ni(II) sites in LDH-[Ni-salen]. The catalysts were reused several times without losing their catalytic activity and selectivity. The present results may provide a convenient strategy for the preparation of 1-tetralone using layered double hydroxide-based heterogeneous catalyst at ambient temperature for industrial application in near future.
文摘Six novel chiral dinuclear Salen complexes[Cu 2 L 1 ·H 2 O(3a),Cu 2 L 2 (3b),Ni 2 L 1 ·2H 2 O(4a),Ni 2 L 2 (4b),Mn 2 Cl 2 L 1 ·H 2 O(5a),Mn 2 Cl 2 L 2 (5b)]have been synthesized(L 1 and L 2 are chiral dimeric Salen ligands with different chain length which were synthesized from(R,R) - diaminocyclohexane,salicylaldehyde,4,4 ’- (1,10 - decaneoxy)sali - cylaldehyde,4,4 ’- (1,6 - hexyloxy)salicylaldehyde).These compounds were charactered by elemental analysis,1 H NMR,FT - IR,UV - Vis and CD spectra.The FT - IR,UV - Vis and CD spectra were discussed and compared with those of monomeric ligand and complex in detail.It was found that the spectra properties of compounds of differ - ent chain length were almost alike,and the properties of dimeric and monomeric compound were similar too.Furthermore Cotton effect and Cotton split of CD spectra of these chiral compounds were explained by the exciton interaction theory.It seemed that the direction of Cotton split depend on the configuration of diaminohexane.(R,R) - diaminohexane determine the chirality of Salen compounds as negative,and the positive and negative compo - nent of Cotton split lie at higher and lower energy respectively.
