An electrochiroptical molecular switch: Mechanistic and kinetic studies

Homar S. Barcena, Biao Liu, Michael V. Mirkin, James Canary

Research output: Contribution to journalArticle

Abstract

Previously, we reported the synthesis and preliminary characterization of Cu(I/II) complexes of N,N-bis(2-quinilylmethyl)-(L)-methionine (Zahn, S.; Canary, J. W. Science 2000, 288, 1404-7). The chemically oxidized and reduced forms of the complexes gave nearly mirror image circular dichroism (CD) spectra as a result of reorganization of the inner coordination sphere of the copper atom. The reorganization involved exchange of oxygen for sulfur in proceeding from the Cu(II) to Cu(I) oxidation state and corresponding ligand conformational changes required to accommodate this exchange. In this paper, we demonstrate that the complex can be triggered by electrochemical means. The electrochemical and stereochemical details of the redox-induced ligand reorganization were probed by independent synthesis of alternative chemical intermediates, CD spectroelectrochemistry, curve fitting of cyclic voltammograms, CD titration, and scanning electrochemical microscopy (SECM). A square-type mechanism was most consistent with the data: the Cu(II) complex is reduced followed by a ligand reorganization step to give the stable reduced form of the complex. The Cu(I) complex is then oxidized in a fast step followed by another ligand reorganization. A millisecond time scale rate was found by SECM for one of the key conformational conversion steps.

Original languageEnglish (US)
Pages (from-to)7652-7660
Number of pages9
JournalInorganic Chemistry
Volume44
Issue number21
DOIs
StatePublished - Oct 17 2005

Fingerprint

Dichroism
switches
Switches
dichroism
Ligands
ligands
Kinetics
kinetics
Microscopic examination
Spectroelectrochemistry
microscopy
Scanning
methionine
scanning
curve fitting
Curve fitting
synthesis
Titration
Sulfur
titration

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

An electrochiroptical molecular switch : Mechanistic and kinetic studies. / Barcena, Homar S.; Liu, Biao; Mirkin, Michael V.; Canary, James.

In: Inorganic Chemistry, Vol. 44, No. 21, 17.10.2005, p. 7652-7660.

Research output: Contribution to journalArticle

Barcena, Homar S. ; Liu, Biao ; Mirkin, Michael V. ; Canary, James. / An electrochiroptical molecular switch : Mechanistic and kinetic studies. In: Inorganic Chemistry. 2005 ; Vol. 44, No. 21. pp. 7652-7660.
@article{195403fe818649478521ab197c72c201,
title = "An electrochiroptical molecular switch: Mechanistic and kinetic studies",
abstract = "Previously, we reported the synthesis and preliminary characterization of Cu(I/II) complexes of N,N-bis(2-quinilylmethyl)-(L)-methionine (Zahn, S.; Canary, J. W. Science 2000, 288, 1404-7). The chemically oxidized and reduced forms of the complexes gave nearly mirror image circular dichroism (CD) spectra as a result of reorganization of the inner coordination sphere of the copper atom. The reorganization involved exchange of oxygen for sulfur in proceeding from the Cu(II) to Cu(I) oxidation state and corresponding ligand conformational changes required to accommodate this exchange. In this paper, we demonstrate that the complex can be triggered by electrochemical means. The electrochemical and stereochemical details of the redox-induced ligand reorganization were probed by independent synthesis of alternative chemical intermediates, CD spectroelectrochemistry, curve fitting of cyclic voltammograms, CD titration, and scanning electrochemical microscopy (SECM). A square-type mechanism was most consistent with the data: the Cu(II) complex is reduced followed by a ligand reorganization step to give the stable reduced form of the complex. The Cu(I) complex is then oxidized in a fast step followed by another ligand reorganization. A millisecond time scale rate was found by SECM for one of the key conformational conversion steps.",
author = "Barcena, {Homar S.} and Biao Liu and Mirkin, {Michael V.} and James Canary",
year = "2005",
month = "10",
day = "17",
doi = "10.1021/ic051048m",
language = "English (US)",
volume = "44",
pages = "7652--7660",
journal = "Inorganic Chemistry",
issn = "0020-1669",
publisher = "American Chemical Society",
number = "21",

}

TY - JOUR

T1 - An electrochiroptical molecular switch

T2 - Mechanistic and kinetic studies

AU - Barcena, Homar S.

AU - Liu, Biao

AU - Mirkin, Michael V.

AU - Canary, James

PY - 2005/10/17

Y1 - 2005/10/17

N2 - Previously, we reported the synthesis and preliminary characterization of Cu(I/II) complexes of N,N-bis(2-quinilylmethyl)-(L)-methionine (Zahn, S.; Canary, J. W. Science 2000, 288, 1404-7). The chemically oxidized and reduced forms of the complexes gave nearly mirror image circular dichroism (CD) spectra as a result of reorganization of the inner coordination sphere of the copper atom. The reorganization involved exchange of oxygen for sulfur in proceeding from the Cu(II) to Cu(I) oxidation state and corresponding ligand conformational changes required to accommodate this exchange. In this paper, we demonstrate that the complex can be triggered by electrochemical means. The electrochemical and stereochemical details of the redox-induced ligand reorganization were probed by independent synthesis of alternative chemical intermediates, CD spectroelectrochemistry, curve fitting of cyclic voltammograms, CD titration, and scanning electrochemical microscopy (SECM). A square-type mechanism was most consistent with the data: the Cu(II) complex is reduced followed by a ligand reorganization step to give the stable reduced form of the complex. The Cu(I) complex is then oxidized in a fast step followed by another ligand reorganization. A millisecond time scale rate was found by SECM for one of the key conformational conversion steps.

AB - Previously, we reported the synthesis and preliminary characterization of Cu(I/II) complexes of N,N-bis(2-quinilylmethyl)-(L)-methionine (Zahn, S.; Canary, J. W. Science 2000, 288, 1404-7). The chemically oxidized and reduced forms of the complexes gave nearly mirror image circular dichroism (CD) spectra as a result of reorganization of the inner coordination sphere of the copper atom. The reorganization involved exchange of oxygen for sulfur in proceeding from the Cu(II) to Cu(I) oxidation state and corresponding ligand conformational changes required to accommodate this exchange. In this paper, we demonstrate that the complex can be triggered by electrochemical means. The electrochemical and stereochemical details of the redox-induced ligand reorganization were probed by independent synthesis of alternative chemical intermediates, CD spectroelectrochemistry, curve fitting of cyclic voltammograms, CD titration, and scanning electrochemical microscopy (SECM). A square-type mechanism was most consistent with the data: the Cu(II) complex is reduced followed by a ligand reorganization step to give the stable reduced form of the complex. The Cu(I) complex is then oxidized in a fast step followed by another ligand reorganization. A millisecond time scale rate was found by SECM for one of the key conformational conversion steps.

UR - http://www.scopus.com/inward/record.url?scp=27544434481&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=27544434481&partnerID=8YFLogxK

U2 - 10.1021/ic051048m

DO - 10.1021/ic051048m

M3 - Article

C2 - 16212392

AN - SCOPUS:27544434481

VL - 44

SP - 7652

EP - 7660

JO - Inorganic Chemistry

JF - Inorganic Chemistry

SN - 0020-1669

IS - 21

ER -