New unsymmetrical μ -phenoxo bridged binuclear copper(II) complexes

A series of binuclear Cu II complexes [Cu 2 XL] n + having two copper(II) ions bridged by different motifs (X = OH − , MeCO 2 − , or Cl − ) have been prepared using the ligands: H 2 L 1 = 4-methyl-2-[ N -(2-{dimethylamino}ethyl- N ′-methyl)aminomethyl]-6-[(prolin-1-yl)methyl]phenol, H 2 L 2 = 4-nitro-2-[ N -(2-{dimethylamino}ethyl- N ′-methyl)aminomethyl]-6-[(prolin-1-yl)methyl]phenol, H 2 L 3 = 4-methyl-2-[ N -(2-{diethylamino}ethyl- N ′-ethyl)aminomethyl]-6-[(prolin-1-yl)methyl]phenol and H 2 L 4 = 4-nitro-2-[ N -(2-{diethylamino}ethyl- N ′-ethyl)aminomethyl]-6-[(prolin-1-yl)methyl]phenol. The complexes have been characterized by spectroscopic, analytical, magnetic and electrochemical measurements. Cryomagnetic investigations (80–300 K) revealed anti-ferromagnetic exchange between the Cu II ions (−2 J in the range −50 to −182 cm −1 ). The strength of anti-ferromagnetic coupling lies in the order: OAc > OH > Cl. Cyclic voltammetry revealed the presence of two redox couples, assigned to Cu II /Cu II /Cu II /Cu I /Cu I /Cu I . The first reduction potential is sensitive to electronic effects from the aromatic ring substituents and steric effect on the donor nitrogens (side arm) of the ligand systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43853/1/11243_2004_Article_5102817.pd

Synthesis of flexible ligands for assembling two metals in close proximity. Magnetic, electrochemical and spectral properties of binuclear copper (II) complexes with different exogenous bridging motifs

Binuclear Cu II complexes having new flexible heptadentate ligands 2,6-bis{[bis(3,3′- N , N -dimethylaminopropyl)amino]methyl}-4-bromophenol [HL 1 ], 2,6-bis(3,3′- N , N -dimethylaminopropyl)amino]methyl}-4-methylphenol [HL 2 ], and 2,6-bis{[bis(3,3′- N , N -dimethylaminopropyl)amino]methyl}-4-methoxyphenol [HL 3 ], capable of assembling two copper ions in close proximity have been synthesized. Comparisons of the charge-transfer (CT) features, observed in electronic spectra of these complexes, are correlated with the electronic effect on the aromatic ring of the ligand systems. Cyclic voltammetry has revealed the existence of two reduction couples, The first is sensitive to the electronic effects of aromatic ring substituents of the ligand system, shifting to more positive potentials when more electrophilic groups replace the existing substituents. The conproportionation constants ( k con ) for the mixed valent Cu I Cu II complexes have been determined electrochemically. The magnetic susceptibilities of the complexes have been measured over the 70–300 K range and the exchange coupling parameter (−2 J ) determined by a least squares fit of the data which indicates an antiferromagnetic spin exchange (−2 J = 94–172 cm −1 ) between the Cu II ions with bridging units in the order: N 3 ≈ NO 2 > OAc > OH.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43852/1/11243_2004_Article_5095478.pd

A novel discrete dinuclear copper(II)–gadolinium(III) complex derived from a Schiff base ligand [Cu(salbn)Gd(NO 3 ) 3 ·H 2 O] (salbn): N , N ′-butylenebis(salicylideaminato)

The synthesis, X-ray and e.p.r. spectral studies of a 3d–4f couple are described here. The crystal structure of [Cu(salbn)Gd(NO 3 ) 3 ·H 2 O], (2) , salbn = N , N ′-butylenebis(salicylideaminato), has been determined by X-ray crystallography. Compound (2) crystallizes in the monoclinic system, space group p21/n, with a = 9.025(1), b = 22.912(1), c = 12.790(1) Å, β = 99.36(1), Z = 4. The deviations of the four coordinating atoms (O(1)O(2)N(1) and N(2) of salbn and the copper atom is displaced from the plane in spite of the lack of any apical ligand. The gadolinium(III) ion is nine-coordinated by the two oxygen atoms of the salbn moiety, three bidentate nitrate ions and one water molecule. The geometry of Gd III can be described as a square antiprism, in which compound Cu II and Gd III are bridged by the two phenolic oxygens of salbn. The Cu II –Gd III distance is 3.269(1) Å. The bridging core CuO2Gd is a butterfly shape. Significant distortion was observed for the complex having the larger diamino string. The title compound exhibits seven e.s.r. transitions with | D | = 0.0467 cm −1 , which demonstrates the existence of zero field splitting. This outcome indicates that compound (2) consists of a perfectly isolated dinuclear Cu–Gd core and steric bulk alters the dihedral angle in the Cu–O–Gd bridge.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43854/1/11243_2004_Article_5115383.pd

Synthesis, spectral, electrochemical and magnetic properties of new asymmetric dicopper(II) complexes bearing chemically distinct coordination sites

Two new unsymmetrical binucleating ligands, 2-[bis(3- N, N -dimethylaminopropyl)-aminomethyl]-6-[prolin-1-yl)methyl]-4-bromophenol [H 2 L 1 ] and 2-[bis(3- N, N -dimethylaminopropyl)aminomethyl]-6-[prolin-1-yl)methyl]-4-methylphenol [H 2 L 2 ], and their dicopper(II) complexes with different exogenous bridging motifs (OAc, Br and Cl) have been prepared and characterized by spectral, electrochemical, magnetic and e.p.r. studies. Electrochemical studies indicate the presence of two irreversible reduction peaks in the cathodic region. Variable temperature magnetic susceptibility studies of the complexes show that the extent of antiferromagnetic coupling increases in the order: OAc − < Cl − < Br − . Broad isotropic or axial symmetric spectral features are observed in powder e.p.r. spectra of the complexes at 77 K. A comparison of the electrochemical and magnetic behaviour of the complexes derived from the ligands is discussed on the basis of an exogenous bridge as well as the substituent at the para position of the phenolic ring.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43855/1/11243_2004_Article_5272793.pd

Contrasting associations between diabetes and cardiovascular mortality rates in low-, middle-, and high-income countries: Cohort study data from 143,567 individuals in 21 countries in the PURE study

Objective: We aimed to compare cardiovascular (CV) events, all-cause mortality, and CV mortality rates among adults with and without diabetes in countries with differing levels of income.Research design and methods: The Prospective Urban Rural Epidemiology (PURE) study enrolled 143,567 adults aged 35-70 years from 4 high-income countries (HIC), 12 middle-income countries (MIC), and 5 low-income countries (LIC). The mean follow-up was 9.0 ± 3.0 years.Results: Among those with diabetes, CVD rates (LIC 10.3, MIC 9.2, HIC 8.3 per 1,000 person-years, P \u3c 0.001), all-cause mortality (LIC 13.8, MIC 7.2, HIC 4.2 per 1,000 person-years, P \u3c 0.001), and CV mortality (LIC 5.7, MIC 2.2, HIC 1.0 per 1,000 person-years, P \u3c 0.001) were considerably higher in LIC compared with MIC and HIC. Within LIC, mortality was higher in those in the lowest tertile of wealth index (low 14.7%, middle 10.8%, and high 6.5%). In contrast to HIC and MIC, the increased CV mortality in those with diabetes in LIC remained unchanged even after adjustment for behavioral risk factors and treatments (hazard ratio [95% CI] 1.89 [1.58-2.27] to 1.78 [1.36-2.34]).Conclusions: CVD rates, all-cause mortality, and CV mortality were markedly higher among those with diabetes in LIC compared with MIC and HIC with mortality risk remaining unchanged even after adjustment for risk factors and treatments. There is an urgent need to improve access to care to those with diabetes in LIC to reduce the excess mortality rates, particularly among those in the poorer strata of society