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Ferrocene‐Conjugated Oxidovanadium(IV) Complexes as Potent Near‐IR Light Photocytotoxic Agents
Author(s) -
Balaji Babu,
Banik Bhabatosh,
Sasmal Pijus K.,
Maity Basudev,
Majumdar Ritankar,
Dighe Rajan R.,
Chakravarty Akhil R.
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201100836
Subject(s) - chemistry , moiety , ferrocene , denticity , crystallography , stereochemistry , terpyridine , conjugated system , dna , crystal structure , medicinal chemistry , metal , electrochemistry , organic chemistry , biochemistry , electrode , polymer
Ferrocene‐conjugated oxidovanadium(IV) complexes [VO(Fc‐tpy)(B)](ClO 4 ) 2 ( 1 – 4 ) and [VO(Ph‐tpy)(dppz)](ClO 4 ) 2 ( 5 ) as a control [Fc = (η 5 ‐C 5 H 4 )Fe II (η 5 ‐C 5 H 5 ), Fc‐tpy = 4′‐ferrocenyl‐2,2′:6′,2″‐terpyridine, Ph‐tpy = 4′‐phenyl‐2,2′:6′,2″‐terpyridine, B = heterocyclic base: 2,2′‐bipyridine (bpy in 1 ), 1,10‐phenanthroline (phen in 2 ), dipyridoquinoxaline (dpq in 3 ), dipyridophenazine (dppz in 4 )] were prepared and their DNA binding, DNA photocleavage activity and photocytotoxicity studied. The crystal structure of [VO(Fc‐tpy)(bpy)](PF 6 ) 2 · 3Me 2 CO shows a vanadyl group in six‐coordinate V IV ON 5 coordination geometry, in which Fc‐tpy and bpy display tridentate meridional and bidentate N ‐donor axial–equatorial binding modes, respectively. The one‐electron paramagnetic complexes exhibit a charge‐transfer band near 590 nm in DMF. The V IV /V III redox couple in 1 – 4 appears near –0.7 V, whereas the Fc moiety shows a response near 0.6 V vs. SCE in DMF/0.1 M TBAP. The complexes are good binders to calf thymus DNA with K b values of 10 4 –10 6 M –1 . DNA melting and viscometric data suggest groove and/or partial intercalative DNA binding of the complexes. Complexes 3 – 5 display DNA photocleavage activity in near‐IR light of 785 nm. Complex 4 shows significant photocytotoxicity in visible light (400–700 nm) in HeLa cells with low dark toxicity.