The calix[4]arene scaffold, blocked in the cone conformation by proper alkylation of the lower rim hydroxyls, was used as a convenient molecular platform for the design of bi- and trimetallic Zn2+ catalysts. The catalytic activity of the Zn2+ complexes of calix[4]arenes decorated at the 1,2-, 1,3-, and 1,2,3-positions of the upper rim with 2,6-bis[(dimethylamino)methyl]pyridine units were investigated in the cleavage of ester 6 and of the RNA model compound HPNP. High rate enhancements, up to 4 orders of magnitude, were observed in a number of catalyst-substrate combinations. Interestingly the order of catalytic efficiency among regioisomeric dinuclear complexes in the cleavage of ester 6 is 1,2-vicinal >> 1,3-distal, but it is reversed in the reaction of HPNP. The higher efficiency of trinuclear compared to dinuclear complexes provides an indication of the cooperation of three Zn2+ ions in the catalytic mechanism.

Di- and trinuclear Zn2+ complexes of calix[4]arene based ligands as catalysts of acyl and phosphoryl transfer reactions / Cacciapaglia, R.; Casnati, Alessandro; Mandolini, L.; Reinhoudt, D. N.; Salvio, R.; Sartori, Andrea; Ungaro, Rocco. - In: JOURNAL OF ORGANIC CHEMISTRY. - ISSN 0022-3263. - 70:(2005), pp. 624-630. [10.1021/jo0487350]

Di- and trinuclear Zn2+ complexes of calix[4]arene based ligands as catalysts of acyl and phosphoryl transfer reactions

CASNATI, Alessandro;SARTORI, Andrea;UNGARO, Rocco
2005-01-01

Abstract

The calix[4]arene scaffold, blocked in the cone conformation by proper alkylation of the lower rim hydroxyls, was used as a convenient molecular platform for the design of bi- and trimetallic Zn2+ catalysts. The catalytic activity of the Zn2+ complexes of calix[4]arenes decorated at the 1,2-, 1,3-, and 1,2,3-positions of the upper rim with 2,6-bis[(dimethylamino)methyl]pyridine units were investigated in the cleavage of ester 6 and of the RNA model compound HPNP. High rate enhancements, up to 4 orders of magnitude, were observed in a number of catalyst-substrate combinations. Interestingly the order of catalytic efficiency among regioisomeric dinuclear complexes in the cleavage of ester 6 is 1,2-vicinal >> 1,3-distal, but it is reversed in the reaction of HPNP. The higher efficiency of trinuclear compared to dinuclear complexes provides an indication of the cooperation of three Zn2+ ions in the catalytic mechanism.
2005
Di- and trinuclear Zn2+ complexes of calix[4]arene based ligands as catalysts of acyl and phosphoryl transfer reactions / Cacciapaglia, R.; Casnati, Alessandro; Mandolini, L.; Reinhoudt, D. N.; Salvio, R.; Sartori, Andrea; Ungaro, Rocco. - In: JOURNAL OF ORGANIC CHEMISTRY. - ISSN 0022-3263. - 70:(2005), pp. 624-630. [10.1021/jo0487350]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/1444627
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