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Unexpected Structure of a Helical N 4 -Schiff-Base Zn(II) Complex and Its Demetallation: Experimental and Theoretical Studies
A new Zn-N -Schiff base L=((±)-trans-N,N'-Bis(2-aminobenzylidene)-1,2-diaminocyclohexane) complex was synthesized and fully characterized, showing an unexpected self-assembled double-stranded helicate structure. The X-ray crystal analysis of the Zn L complex ((C H N Zn ,CH Cl , a=14.2375(3) Å,...
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Published in: | Chemphyschem 2018-11, Vol.19 (21), p.2938-2946 |
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Main Authors: | , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | A new Zn-N
-Schiff base L=((±)-trans-N,N'-Bis(2-aminobenzylidene)-1,2-diaminocyclohexane) complex was synthesized and fully characterized, showing an unexpected self-assembled double-stranded helicate structure. The X-ray crystal analysis of the Zn
L
complex ((C
H
N
Zn
,CH
Cl
, a=14.2375(3) Å, b=16.7976(4) Å, c=16.1613(4) Å, monoclinic, P2
/n, Z=4) shows a centrosymmetrical structure in which zinc atoms are in distorted tetrahedral environments, revealing an M- (R, R) left-handed helicity in its asymmetric unit. However, it was observed that this dinuclear complex is thermodynamically unstable in the presence of small water amounts and undergoes demetallation into free N4-Schiff base ligand and ZnO nanoparticles. This hydrolysis process was thoroughly identified and monitored through detailed
H NMR, DOSY NMR analysis. The reaction mechanism of this demetallation event was elucidated by using the DFT method, involving an activation energy smaller than 13 kcal/mol. Besides, a theoretical mechanism of the demetallation process is given for the first time. |
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ISSN: | 1439-4235 1439-7641 |
DOI: | 10.1002/cphc.201800514 |