title: Photochemistry and DNA-affinity of some pyrimidine-substituted styryl-azinium iodides.
abstract: The relaxation properties of the excited states of three iodides of trans-1,2-diarylethene analogues (where one aryl group is a methylpyridinium, methylquinolinium or dimethylimidazolium group and the other one is a phenyl ring para-substituted by a pyrimidine ring) have been investigated in buffered (pH = 7) aqueous solution. As found in previous works for several analogues, these quaternized salts undergo efficient trans→cis photoisomerization while the yield of the radiative deactivation is very small at room temperature. The solvent effect on the spectral behaviour indicates the occurrence of intramolecular charge transfer which can induce interesting non-linear optical properties. The results of a study of the interactions of these salts with DNA, which might affect the cell metabolism, showed a relatively modest binding affinity for the pyridinium and imidazolium salts and a more substantial affinity for the quinolinium analogue. The formation of ligand-DNA complexes affects only slightly the radiative relaxation yield while leading to a relevant reduction of the isomerization yield. Measurements of the linear dichroism behaviour of the three compounds and comparison with three analogues bearing furan or thienyl groups, which have been found to display different affinity with DNA in previous works, gave interesting information on the nature of the ligand-DNA binding of these compounds.
authors: Dipartimento di Chimica and Centro di Eccellenza Materiali Innovativi Nanostrutturati, Università di Perugia, Italy.
authors: Alessandra
authors: A
authors: Mazzoli
authors: Benedetta
authors: B
authors: Carlotti
authors: Carmela
authors: C
authors: Bonaccorso
authors: Cosimo G
authors: CG
authors: Fortuna
authors: Ugo
authors: U
authors: Mazzucato
authors: Giorgia
authors: G
authors: Miolo
authors: Anna
authors: A
authors: Spalletti
mesh_terms: D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D007454:Iodides / Q000737:chemistry; D007536:Isomerism; D011726:Pyridinium Compounds / Q000737:chemistry*; D011743:Pyrimidines / Q000737:chemistry*; D011789:Quantum Theory; D011806:Quinolinium Compounds / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007093:Imidazoles; D007454:Iodides; D011726:Pyridinium Compounds; D011743:Pyrimidines; D011806:Quinolinium Compounds; C029899:imidazole; D004247:DNA; C030986:pyrimidine