Abstract
The binuclear copper(II) complex [Cu2(RSSR)2] (1), where RSSR is a dianionic Schiff base derived from 2-(thioethyl)salicylaldimine having a disulfide bond is prepared, structurally characterized by X-ray crystallography and its photo-induced DNA cleavage activity studied. The Schiff base ligand H2RSSR is also structurally characterized. The crystal structure of 1 shows the discrete dimeric nature of the complex with each metal showing square-planar geometry with a CuN2O2 coordination (Cu⋯Cu, 5.011(1) Å). The tetradentate Schiff base RSSR acts as a linker of two copper centers. The sulfur atoms in the disulfide unit do not show any apparent interaction with the metal ion. Complex 1, which is cleavage inactive in the dark in the presence of reducing agents, shows significant cleavage of supercoiled pUC19 DNA on exposure to UV light of 312 nm or visible light of different wavelengths under aerobic conditions, in the absence of any additives. DNA cleavage data from control experiments reveal involvement of the disulfide unit as a photosensitizer undergoing photo-induced S-S bond cleavage on exposure to UV light and the resulting species activates molecular oxygen to form singlet oxygen (1O2) that causes DNA cleavage following a type-II process. Photo-induced DNA cleavage by 1 on red-light exposure using a CW laser of 632.8 nm or a pulsed ruby laser of 694 nm is proposed to involve sulfide radicals in a type-I process and hydroxyl radicals as the reactive species.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 344-348 |
| Number of pages | 5 |
| Journal | Dalton Transactions |
| Issue number | 2 |
| DOIs | |
| State | Published - Jan 21 2005 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Inorganic Chemistry
Cite this
Designing molecules for PDT : Red light-induced DNA cleavage on disulfide bond activation in a dicopper(n) complex. / Dhar, Shanta; Nethaji, Munirathinam; Chakravarty, Akhil R.
In: Dalton Transactions, No. 2, 21.01.2005, p. 344-348.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Designing molecules for PDT
T2 - Red light-induced DNA cleavage on disulfide bond activation in a dicopper(n) complex
AU - Dhar, Shanta
AU - Nethaji, Munirathinam
AU - Chakravarty, Akhil R.
PY - 2005/1/21
Y1 - 2005/1/21
N2 - The binuclear copper(II) complex [Cu2(RSSR)2] (1), where RSSR is a dianionic Schiff base derived from 2-(thioethyl)salicylaldimine having a disulfide bond is prepared, structurally characterized by X-ray crystallography and its photo-induced DNA cleavage activity studied. The Schiff base ligand H2RSSR is also structurally characterized. The crystal structure of 1 shows the discrete dimeric nature of the complex with each metal showing square-planar geometry with a CuN2O2 coordination (Cu⋯Cu, 5.011(1) Å). The tetradentate Schiff base RSSR acts as a linker of two copper centers. The sulfur atoms in the disulfide unit do not show any apparent interaction with the metal ion. Complex 1, which is cleavage inactive in the dark in the presence of reducing agents, shows significant cleavage of supercoiled pUC19 DNA on exposure to UV light of 312 nm or visible light of different wavelengths under aerobic conditions, in the absence of any additives. DNA cleavage data from control experiments reveal involvement of the disulfide unit as a photosensitizer undergoing photo-induced S-S bond cleavage on exposure to UV light and the resulting species activates molecular oxygen to form singlet oxygen (1O2) that causes DNA cleavage following a type-II process. Photo-induced DNA cleavage by 1 on red-light exposure using a CW laser of 632.8 nm or a pulsed ruby laser of 694 nm is proposed to involve sulfide radicals in a type-I process and hydroxyl radicals as the reactive species.
AB - The binuclear copper(II) complex [Cu2(RSSR)2] (1), where RSSR is a dianionic Schiff base derived from 2-(thioethyl)salicylaldimine having a disulfide bond is prepared, structurally characterized by X-ray crystallography and its photo-induced DNA cleavage activity studied. The Schiff base ligand H2RSSR is also structurally characterized. The crystal structure of 1 shows the discrete dimeric nature of the complex with each metal showing square-planar geometry with a CuN2O2 coordination (Cu⋯Cu, 5.011(1) Å). The tetradentate Schiff base RSSR acts as a linker of two copper centers. The sulfur atoms in the disulfide unit do not show any apparent interaction with the metal ion. Complex 1, which is cleavage inactive in the dark in the presence of reducing agents, shows significant cleavage of supercoiled pUC19 DNA on exposure to UV light of 312 nm or visible light of different wavelengths under aerobic conditions, in the absence of any additives. DNA cleavage data from control experiments reveal involvement of the disulfide unit as a photosensitizer undergoing photo-induced S-S bond cleavage on exposure to UV light and the resulting species activates molecular oxygen to form singlet oxygen (1O2) that causes DNA cleavage following a type-II process. Photo-induced DNA cleavage by 1 on red-light exposure using a CW laser of 632.8 nm or a pulsed ruby laser of 694 nm is proposed to involve sulfide radicals in a type-I process and hydroxyl radicals as the reactive species.
UR - http://www.scopus.com/inward/record.url?scp=12444304259&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=12444304259&partnerID=8YFLogxK
U2 - 10.1039/b413410a
DO - 10.1039/b413410a
M3 - Article
C2 - 15616724
AN - SCOPUS:12444304259
SP - 344
EP - 348
JO - Dalton Transactions
JF - Dalton Transactions
SN - 1477-9226
IS - 2
ER -