Antibacterial properties of phosphine gold(I) complexes with 5-fluorouracil

New gold(I) complexes with coordination to 5-fluorouracil (5-FU), an anticancer drug with antibacterial properties, have been synthesised and characterised, and are the first reported examples of 5-FU-Au compounds. These new complexes show high solution stability, even in the presence of a cysteine derivative, and so were evaluated as antibacterial compounds against model Gram-positive and Gram-negative bacteria. All the complexes show excellent antibacterial activity against Gram-positive B. subtilis, most of them improving the activity of 5-FU alone. Furthermore, these new complexes are also active against Gram-negative E. coli, where [Au(5-FU)(PTA)], the complex with the smallest phosphane, is the most bactericidal, 32 times more active than 5-FU on its own.

Experimental and theoretical study of novel amino-functionalized P(V) coordination compounds suggested as inhibitor of MPro of SARS-COV-2 by molecular docking study

Amino-functionalized P(V) derivatives providing both N- and O-donor modes have attracted interest owing to their potential to form interesting coordination assemblies with applications such as biological drugs. Novel coordination modes of two- and four-dentate tris (pyridin-2-yl)phosphoric triamide OP[NH-2Py]3 as ([Co(II){[O][NH-2Py]P(O)[Ph]}2(DMF)2], 1) and ([Cu(II)Cl{[NH-2Py]2P(O)[N-2Py]}].DMF, 2) have been synthesized and structurally studied. The metal center environment is distorted octahedral for 1 and distorted square pyramidal for 2. The crystal structure of a new complex of Cu(II) with a Cu[N]4[Cl]2 environment ([Cu(II)Cl2(Pyrazole)4], 3) is also investigated. An evaluation of the inhibitory effect against the coronavirus (Main Protease [MPro] of SARS-CoV-2) was carried out by a molecular docking study and illustrates that these compounds have a good interaction tendency with CoV-2, where 1 has the best binding affinity with the biological target comparable with other SARS-CoV-2 drugs. Moreover, theoretical QTAIM and natural bond orbital (NBO) calculations are used to evaluate the metal-oxygen/-nitrogen bonds suggesting that they are mainly electrostatic in nature with a slight covalent contribution. A molecular packing analysis using Hirshfeld surface (HS) analysis shows that N-H … O (in 1 and 2) and N-H … Cl (in 3) hydrogen bonds are the dominant interactions that contribute to the crystal packing cohesion. The semi-empirical PIXEL method indicates that the electrostatic and repulsion energy components in the structures of 1 and 2 and the dispersion and electrostatic components in that of 3 are the major contributors to the total lattice energy.

The first coordination polymers with an [O]2[N]P(S)-Hg segment: a combined experimental, theoretical and database study

The study of one-dimensional coordination polymers {Hg₂Cl₄L₁}_n (1), {HgBr₂L₁}_n (2) and {Hg₂Cl₄L₂}_n (3) (L₁ = (S)P(OC₂H₅)₂NHC₆H₄NHP(S)(OC₂H₅)₂ and L₂ = (S)P(OC₂H₅)₂NC₄H₈NP(S)(OC₂H₅)₂) is the first such structural study of Hg(ii) coordination polymers with (O)₂(N)PS-based ligands. The mercury atoms adopt a distorted trigonal pyramidal environment, Hg(Cl)₃(S) for 1 and 3 and Hg(Br)₂(S)₂ for 2, and the difference observed in the stoichiometry of mercury halide to the thiophosphoramide ligand in 1 and 3 with respect to the one in 2 is a result of the formation of the Hg₂Cl₂ ring, however, the molar ratio 2 : 1 of HgX₂ (X = Cl and Br) to ligand was used for the preparation of all three complexes. The strengths of mercury-sulfur and mercury-halide covalent bonds are evaluated by theoretical calculations (QTAIM and NBO) which show their principally electrostatic nature with a partial covalent contribution. The energies of interactions building supramolecular assemblies and intramolecular interactions, i.e. NHCl, NHBr, CHCl, CHBr, CHO, CHS and CHπ, are theoretically evaluated. The characteristic structural features arising from the aromatic/aliphatic linkers in the ligands and chloride/bromide attached to mercury are investigated by Hirshfeld surface analysis and fingerprint plots.

α-methylation and α-fluorination electronic effects on the regioselectivity of carbonyl groups of uracil by H and triel bonds in the interaction of U, T and 5FU with HCl and TrH3 (Tr = B, Al)

Quantum chemical calculations at the ωB97XD/6-311++G(d,p) level of theory have been executed to investigate the effect of substituents via hydrogen-bonded and triel-bonded complexes between uracil (U), thymine (T) and 5-fluorouracil (5FU) with HCl for the former complexes, and with BH₃ and AlH₃ for the latter complexes. These calculations are supported by single-point energy calculations at MP2/6-311++G(d,p) and CCSD/6-31 + G(d,p) levels of theory, Natural Bond Orbital (NBO) and Molecular Electrostatic Potentials (MEPs) analyses, and global/local reactivity descriptors. The results reveal that triel-bonded complexes are strongly bounded than hydrogen-bonded ones, and Al-containing dimers stronger than B-containing ones. In addition, as the central triel atom grows in size, B-containing dimers (B-O triel bond) are accompanied by weak B-H⋯O unconventional H-bonds. According to local reactivity descriptors, the B-O triel bond is hard-hard interaction that indicates that the association is primarily charge controlled, while the Al-O triel bond is soft-soft interaction that is primarily orbital controlled. In both Hydrogen as well as triel-bonded complexes, the α-methylation slightly overestimates the binding strength of U, while the α-fluorination exerts the opposite role by underestimating the binding strength of U. In overall, the effect of substituents on the bond strength and thus on the regioselectivity is very small, suggesting a competition between the two carbonyl groups in terms of structures and binding energies.

Experimental observation and theoretical investigation of a novel Cd(ii) complex with π-hole interactions involving nitro groups

A cadmium(ii) complex, which represents a novel example of supramolecular system bearing a network of π-hole interactions, has been synthesized.