2086-62-6Relevant articles and documents
Photophysical studies on covalently-linked naphthalene and TEMPO free radical systems: Observation of a charge transfer state in the ground state
Rane, Vinayak,Kundu, Sushma,Das, Ranjan
, p. 1351 - 1361 (2015)
A series of molecules containing a naphthalene chromophore and a stable free radical 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) covalently linked by a spacer group of different lengths have been synthesized. In n-hexane solution, their photophysical behavior was studied and compared with a system of freely moving naphthalene and the free radical TEMPO. The linked molecules showed strong quenching of the singlet and triplet states of the naphthalene moiety, compared to when naphthalene and TEMPO were not linked. The quenching efficiency decreased with increasing the length of the spacer group. In addition, new electronic absorption and emission bands, along with the usual bands of the individual moieties, were also seen. These news bands have been attributed to the formation of electron donor-acceptor charge-transfer complexes in the ground state, arising from the interaction between the two moieties in close proximity. The photophysical dynamics of the linked molecules has been rationalized by assuming the existence of two types of population of the linked molecules: folded and extended. The ground state complex formation is proposed to occur only in the folded conformation of the linked molecules. To our knowledge, this is possibly the first example of a ground state charge-transfer complex formation involving a TEMPO free radical and naphthalene.
Mutagenicity of N-acyloxy-N-alkoxyamides as an indicator of DNA intercalation part 1: Evidence for naphthalene as a DNA intercalator
Banks, Tony M.,Clay, Samuel F.,Glover, Stephen A.,Schumacher, Rhiannon R.
supporting information, p. 3699 - 3714 (2016/05/09)
N-Acyloxy-N-alkoxyamides are direct-acting mutagens in S. typhimurium TA100 with a linear dependence upon log P that maximises at log P0 = 6.4. Eight N-acyloxy-N-alkoxyamides (2-9) bearing a naphthalene group on any of the three side-chains and with log P0 6.4 have been demonstrated to be significantly and uniformly more mutagenic towards S. typhimurium TA100 than 50 mutagens without naphthalene. The activity enhancement of 2-9 is likely due to intercalative binding of naphthalene to bacterial DNA as a number are also active in TA98, a frame-shift strain of S. typhimurium, which is modified by intercalators. DNA damage profiles for naphthalene-bearing mutagens confirm enhanced reactivity with DNA when naphthalene is incorporated and a different binding mode when compared to mutagens without naphthalene. The effect is independent of whether the naphthalene is attached to an electron-donating alkyl or electron-withdrawing acyl group, alkyl tether length or, in the case of 6 and 7, the point of attachment to naphthalene. A new quantitative structure activity relationship has been constructed for all 58 congeners incorporating log P and an indicator variable, I, for the presence (I = 1) or absence (I = 0) of naphthalene and from which the activity enhancing effect of a naphthalene has been quantified at between three and four log P units. Contrary to conventional views, simple naphthalene groups could target molecules to DNA through intercalation.
Plasticity of the Nickel(II) coordination environment in complexes with hemilabile phosphino thioether ligands
MacHan, Charles W.,Spokoyny, Alexander M.,Jones, Matthew R.,Sarjeant, Amy A.,Stern, Charlotte L.,Mirkin, Chad A.
body text, p. 3023 - 3033 (2011/04/24)
A series of homoligated Ni(II) complexes formed from two phosphino thioether (P,S) chelating ligands has been synthesized and characterized. Interestingly, this included octahedral Ni(II) complexes which, unlike previously characterized d8 Rh(I), Pt(II), and Pd(II) analogues, exhibit in situ exchange processes centered around chloride ligand dissociation. This was verified and studied through the controlled abstraction from and introduction of chloride ions to this system, which showed that these processes proceed through complexes with square pyramidal, tetrahedral, and square planar geometries. These complexes were studied with a variety of characterization methods, including single-crystal X-ray diffraction studies, solution 31P{1H} NMR spectroscopy, UV-vis spectroscopy, and DFT calculations. A general set of synthetic procedures that involve the use of coordinating and noncoordinating counteranions, as well as different hemilabile ligands, to mediate geometry transformations are presented.
