A method is presented for the efficient evaluation of long-range electrostatic forces in combined quantum mechanical and molecular mechanical (QM/MM) calculations of periodic systems. The QM/MM-Ewald method is a linear-scaling electrostatic method that utilizes the particle mesh Ewald algorithm for calculation of point charge interactions of molecular mechanical atoms and a real-space multipola...

The asymmetric unit of the title compound, C(6)H(16)N(+)·C(3)H(2)N(3)S(3) (-), contains two independent ion pairs. The 2,4,6-trithioxo-1,3,5-triazinan-1-ide anion features an almost planar six-membered ring (r.m.s. deviations = 0.009 and 0.018 Å) having exocyclic double-bond S atoms. The anions inter-act by N-H⋯S hydrogen bonds to generate a chain running along [110]. The triethyl-ammonium cati...

The asymmetric unit of the title compound, C(12)H(24)N(+)·C(9)H(8)N(3)O(2) (-), consists of two dicyclo-hexyl-ammonium cations linked to two (S)-2-azido-3-phenyl-propano-ate anions by four short N-H⋯O hydrogen bonds with N⋯O distances in the range 2.712 (3)-2.765 (3) Å. The dicyclo-hexyl-ammonium cations and the aryl and carboxyl-ate groups of the anion are related by a pseudo-inversion centre,...

The standard molar enthalpy of combustion (Δc H (o) m) and formation (Δf H (o) m) of quaternary ammonium tetrachlorozincate [n-CnH2n+1N(CH3)3]2ZnCl4 have been determined for the hydrocarbon chain length from even number 8 to 18 of carbon atoms (n) by an oxygen-bomb combustion calorimeter. The results indicated that the values of Δc H (o) m increased and Δf H (o) m decreased with increasing chai...

In the title salt, [(CH3CH2CH2)2NH2]4[Sn(C2O4)4]·H2O, the Sn(IV) atom of the stannate anion is located on a special position with -42m symmetry. It is eight-coordinated by four chelating oxalate anions. The di-propyl-ammonium cation possesses mirror symmetry while the lattice water mol-ecule is disordered about a position with -42m symmetry and has an occupancy of 0.25. In the crystal, the anio...

Hydrazinolysis of unactivated amide bonds is significantly accelerated by the addition of ammonium salts. The reactions proceed at 50-70 °C to give amines with broad substrate scope that outperforms existing amide bond cleavage reactions. Application to peptide and amino sugar derivatives is also demonstrated.

Gene methylation is an important mechanism regulating gene expression and genome stability. Our previous work showed that methylation of the nitrate reductase (NR) gene NIA2 was dependent on chromomethylase 3 (CMT3). Here, we show that CMT3-mediated NIA2 methylation is regulated by ammonium in Arabidopsis thaliana. CHG sequences (where H can be A, T, or C) were methylated in NIA2 but not in NIA...

A simple, accurate, sensitive and rapid method for the determination of some aromatic amines in either the pure form or in pharmaceutical formulation or in biological fluids or in waste water sample is proposed. The method is based on the formation of colored compounds with sodium 1,2-naphthoquinone-4-sulphonate and cetyltrimethyl ammonium bromide in alkaline medium. Beer’s law of colored speci...

The title compound, C(17)H(13)N(3)OS, was obtained by the reaction of benzoyl chloride, ammonium thio-cyanate and 5-amino-quinoline in the presence of polyethyl-eneglycol-400 (PEG-400) as a phase-transfer catalyst. The compound crystallized as discrete mol-ecules linked by N-H⋯N and C-H⋯N hydrogen bonds involving all the potential donors, generating sheets parallel to (100). An intramolecular N...

In the course of stuidies of ammonia absorption from the gastrointestinal tract in cirrlhosis it was notedl that the hiiglhest arterial ammonia levels were achieved slhortly after oral ingestioni of ammonium clhloride. Peak values usually occurred witlhin 15 min of adnministration. The rapid appearance time of the zenith was surprising in view of previous studies of ammonia tolerance, whiclh lh...