Ligand‐Flexibility Controlled and Solvent‐Induced Nuclearity Conversion in Cu II ‐Based Catecholase Models: A Deep Insight Through Combined Experimental and Theoretical Investigations
| Autor: | Debasis Das, Prateeti Chakraborty, Ennio Zangrando, Sanchari Dasgupta, Antonio Bauzá, Ishani Majumder, Antonio Frontera |
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| Přispěvatelé: | Dasgupta, Sanchari, Majumder, Ishani, Chakraborty, Prateeti, Zangrando, Ennio, Bauza, Antonio, Frontera, Antonio, Das, Debasis |
| Rok vydání: | 2016 |
| Předmět: |
Reduced Schiff base
Metalloenzyme Metalloenzymes Reduced Schiff bases Solvent effect 010402 general chemistry Photochemistry 01 natural sciences Redox Medicinal chemistry Catecholase activity Copper Density functional calculations Enzyme models Nuclearity conversion Schiff bases Solvent effects Inorganic Chemistry Catalysis Schiff base chemistry.chemical_compound Phenol Dicyanamide 010405 organic chemistry Chemistry Ligand Enzyme model 0104 chemical sciences Solvent Density functional calculation |
| Zdroj: | European Journal of Inorganic Chemistry. 2017:133-145 |
| ISSN: | 1099-0682 1434-1948 |
| DOI: | 10.1002/ejic.201600985 |
| Popis: | A Schiff-base ligand, 4-bromo-2-[(2-hydroxy-1,1-dimethylethylimino)methyl]phenol (HL1), and its reduced analogue 4-bromo-2-[(2-hydroxy-1,1-dimethylethylamino)methyl]phenol (HL2) have been synthesized. Treatment of HL1 and HL2 with Cu(ClO4)2·6 H2O in the presence of sodium dicyanamide in MeOH and MeCN has been investigated. HL1 generates [Cu(L1)(MeOH)(dca)] (1) in MeOH (dca = dicyanamide) but [Cu2(L1)2(dca)2] (2) in MeCN. HL2 in MeOH produces [Cu4(L2)4(MeOH)2(ClO4)2] (3). On the other hand, in MeCN an interesting redox reaction is observed. CuII undergoes reduction, and [CuI(MeCN)4](ClO4) (4) is formed with concomitant oxidation of HL2 to HL1. The solvent-dependent nuclearity change (i.e, conversion of mononuclear species 1 into dinuclear species 2) has been investigated by ESI-MS, through the addition of MeCN to a methanolic solution of 1, and the origin of the conversion has been explained by means of DFT calculations. The catecholase activity of 1, 2 and 3 in MeCN and DMF has been investigated with the model substrates 3,5-di-tert-butylcatechol (3,5-DTBC), tetrachlorocatechol (TCC) and pyrocatechol (PRC). Compound 1 is inactive with all substrates, whereas 2 is active only with 3,5-DTBC in DMF. In contrast, 3 – which exists as a dinuclear species in solution, as is evident from ESI-MS – is highly active with all three substrates, especially in MeCN. The exceptionally high catalytic activity of 3 over 2 is likely to be due to the higher flexibility of the reduced Schiff-base ligand in comparison with its Schiff base analogue. |
| Databáze: | OpenAIRE |
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