Electronic structure calculations have been performed to investigate the initial steps in the gas-phase decomposition of urea and urea nitrate. The most favorable decomposition pathway for an isolated urea molecule leads to HNCO and NH3. Gaseous urea nitrate formed by the association of urea and HNO3 has two isomeric forms, both of which are acid-base complexes stabilized by the hydrogen-bondin...

The asymmetric unit, 2CH(4)N(2)O·C(7)H(12)O(4), of the title cocrystal contains one urea mol-ecule and a half-mol-ecule of pimelic acid; the latter, together with a second urea mol-ecule, are completed by symmetry, with the central atom of the whole pimelic acid moiety placed on a twofold crystallographic axis. The crystal packing is stabilized by O-H⋯O and N-H⋯O hydrogen-bond, generating a cha...

The asymmetric unit of the title compound, C(14)H(7)Cl(3)F(2)N(2)O(2), contains two unique molecules. The 2,3,5-trichloro-phenyl ring is almost coplanar with the urea group in both molecules, whereas the 2,6-difluoro-phenyl ring is twisted from the urea plane by 54.83 (10)° in one molecule and 60.58 (10)° in the other. An intra-molecular N-H-O hydrogen bond stabilizes the mol-ecular conformatio...

In the N-substituted benzoyl-thio-urea, C(24)H(23)N(5)OS, the benzoyl-thio-urea unit is non-planar (r.m.s. deviation = 0.126 Å). The aliphatic part of the tetra-hydro-quinoline fused-ring system is disordered over two positions in a 0.592 (5):0.408 (5) ratio. The pyridine and pyrrole rings are twisted by 55.2 (1)° in order to avoid crowding of their respective substituents. Pairs of mol-ecules ...

In the title compound, C(16)H(12)N(2)O(2)S, the carbonyl-thio-urea group forms dihedral angles of 75.4 (1) and 13.1 (2)°, respectively, with the naphthalene ring system and furan ring. The mol-ecule adopts a trans-cis configuration with respect to the positions of the furoyl and naphthyl groups relative to the S atom across the thio-urea C-N bonds. This geometry is stabilized by an N-H⋯·O intra...

In the title compound, C(17)H(20)N(2)O(4), the 2,5-dimeth-oxy-phenyl unit is almost planar, with an r.m.s. deviation of 0.015 Å. The dihedral angle between the 2,5-dimeth-oxy-phenyl ring and the urea plane is 20.95 (8)°. The H atoms of the urea NH groups are positioned syn to each other. The mol-ecular structure is stabilized by a short intra-molecular N-H⋯O hydrogen bond. In the crystal, inter...

Urea and its derivatives have been the subject of extensive experimental and theoretical studies, using many techniques, mainly because of interesting physical and chemical properties [1-4]. Here we report a preliminary results of charge density study of N-phenylurea using synchrotron diffraction data collected at beamline F1 at HASYLAB/DESY. Although known from literature [1], the structure wa...

We use long multiple trajectories generated by molecular dynamics simulations to probe the stability of oligomers of A 16–22 (KLVFFAE) peptides in aqueous urea solution. High concentration of urea promotes the formation of -strand structures in A 16–22 monomers, whereas in water they adopt largely compact random coil structures. The tripeptide system, which forms stable antiparallel -sheet stru...

The molecular mechanism of urea-induced protein denaturation is not yet fully understood. Mainly two opposing mechanisms are controversially discussed, according to which either hydrophobic, or polar interactions are the dominant driving force. To resolve this question, we have investigated the interactions between urea and all 20 amino acids by comprehensive molecular dynamics simulations of 2...

Urea lesions are formed in DNA because of free radical damage of the thymine base, and their occurrence in DNA blocks DNA polymerases, which has deleterious consequences. Recently, it has been shown that urea is capable of forming hydrogen bonding and stacking interactions with nucleobases, which are responsible for the unfolding of RNA in aqueous urea. Base pairing and stacking are inherent pr...