The paper reports results of 'H and "C high-resolution nuclear magnetic resonance studies of nifedipine and signal assignment to particular atoms. High-resolution 'H NMR spectra with no signals attributed to protons in weak fields (S= 10-12 ppm) imply that H7 atom is strongly connected to the ring and is not involved in the formation of hydrogen bonds.

No abstract

No abstract

No abstract

Electron spin resonance in some charge-transfer complexes of 7,7,8,5-tetracyanoquinodimethane (TCNQ) with sulphanilamides and antibiotics has been investigated.The ESR spectra are caused by two types of parainagnetic centres: the impurity type and the thermally excited type (Wannier spin excitons).CRYSTALLINE charge-transfer complexes formed from a diamagnetic electron donor and an electron acceptor are usually strongly antiferromagnetically coupled. These crystals c m be described by the Heisenberg Hamiltonian for antiferromagnetics, where 6 is a parameter (0 < S < l), connected with the energy of interaction between spins, J is the exchange integral, Sj is the spin operator for thej-th free radical, N / 2