2-Aminoterephthalic acid dimethyl ester

Single crystals of the title compound, C10H11NO4, an inter­mediate in the industrial synthesis of yellow azo pigments, were obtained from the industrial production. The mol­ecules crystallize as centrosymmetic dimers connected by two symmetry-related N—H⋯O=C hydrogen bonds. Each mol­ecule also contains an intra­molecular N—H⋯O=C hydrogen bond. The dimers form stacks along the a-axis direction. Neighbouring stacks are arranged into a herringbone structure

Cu-based metalorganic systems: an ab initio study of the electronic structure

Within a first principles framework, we study the electronic structure of the recently synthesized polymeric coordination compound Cu(II)-2,5-bis(pyrazol-1-yl)-1,4-dihydroxybenzene (CuCCP), which has been suggested to be a good realization of a Heisenberg spin-1/2 chain with antiferromagnetic coupling. By using a combination of classical with ab initio quantum mechanical methods, we design on the computer reliable modified structures of CuCCP aimed at studying effects of Cu-Cu coupling strength variations on this spin-1/2 system. For this purpose, we performed two types of modifications on CuCCP. In one case, we replaced H in the linker by i) an electron donating group (NH2) and ii) an electron withdrawing group (CN), while the other modification consisted in adding H2O and NH3 molecules in the structure which change the local coordination of the Cu(II) ions. With the NMTO-downfolding method we provide a quantitative analysis of the modified electronic structure and the nature of the Cu-Cu interaction paths in these new structures and discuss its implications for the underlying microscopic model.Comment: 18 pages, 11 figures, final versio