| Autor: |
Biswas B; Department of Chemistry, Kazi Nazrul University, Asansol 713340, West Bengal, India.; Department of Chemistry, Hooghly Mohsin College, Chinsurah 712101, West Bengal, India., Siddiqui AI; Department of Chemistry, IIT Gandhinagar, Palaj 382355, Gujarat, India., Majee MC; Department of Chemistry, BB College, Asansol 713303, West Bengal, India., Saha SK; Department of Chemistry, Kazi Nazrul University, Asansol 713340, West Bengal, India., Mondal B; Department of Chemistry, IIT Gandhinagar, Palaj 382355, Gujarat, India., Saha R; Department of Chemistry, Kazi Nazrul University, Asansol 713340, West Bengal, India.; Departamento de Química Inorgánica, Universidad de Valencia, Burjasot, Valencia 46100, Spain., Gómez García CJ; Departamento de Química Inorgánica, Universidad de Valencia, Burjasot, Valencia 46100, Spain. |
| Abstrakt: |
We present a bifunctional heptanuclear cobalt(II)/cobalt(III) molecular complex formulated as [Co 7 (μ 3 -OH) 4 (H 2 L 1 ) 2 (HL 2 ) 2 ](NO 3 ) 6 ·6H 2 O ( 1 ) (where H 5 L 1 is 2,2'-(((1E,1'E)-((2-hydroxy-5-methyl-1,3-phenylene)bis(methanylylidene))bis(azanylylidene))bis(propane-1,3-diol)) and H 2 L 2 is 2-amino-1,3-propanediol). Compound 1 has been characterized by single-crystal X-ray diffraction analysis along with other spectral and magnetic measurements. Structural analysis indicates that 1 contains a mixed-valence Co 7 cluster where a central Co(II) ion is connected to six different Co centers (four Co III and two Co II ions) by four μ 3 -OH groups, giving rise to a planar heptanuclear cluster that resembles a molecular fragment of a layered double hydroxide (LDH). Two triply deprotonated (H 2 L 1 ) 3- ligands form the outer side of the cluster while two singly deprotonated (HL 2 ) - ligands are located at the top and bottom of the central heptanuclear core. Variable temperature magnetic measurements indicate the presence of weak ferromagnetic Co II ···Co II interactions ( J = 3.53(6) cm -1 ) within the linear trinuclear Co II cluster. AC susceptibility measurements show that 1 is a field-induced single-molecule magnet (SMM) with τ 0 = 8.2(7) × 10 -7 s and U eff = 11.3(4) K. The electrocatalytic hydrogen evolution reaction (HER) activity of 1 in homogeneous phase shows an overpotential of 455 mV, with a Faradaic efficiency of 81% and a TOF of 8.97 × 10 4 μmol H 2 h -1 mol -1 . |
