Stability Of Molecular Systems Research Articles

Structure, Spectroscopy, and Theoretical insights on Co-crystals of 2,4-Diamino-6-Methyl-1,3,5-Triazine Bis(4-Aminobenzoic acid) Monohydrate as a promising anti-cancer agent

Co-crystals of 2,4-diamino-6-methyl-1,3,5-triazine bis (4-aminobenzoic acid) monohydrate (hereafter named DMTAB) have been grown from a slow solvent method at room temperature. Single crystal XRD reveals the centrosymmetric nature of the grown crystal with the P21/n space group. Hirshfeld Surface analysis has been performed to visualize and analyse the spatial distribution of intermolecular interactions in a molecular system. The presence of functional groups has been analysed with Fourier Transform Infrared and Raman studies. By employing NBO analysis, valuable insights into the nature of chemical bonds, electron delocalization, and the overall stability of molecular systems have been examined. Theoretical UV–Vis spectrum studies using Time-Dependent - Density Functional Theory (TD-DFT) in different solvents provide a valuable computational tool to predict and understand the electronic transitions of molecules. HOMO-LUMO analysis and density of states spectrum in different solvents further shed light on the electronic structure and reactivity of molecules in their surroundings. First-order hyperpolarizability calculations have been used to analyse the nonlinear optical response of a grown material. Molecular docking studies were conducted to anticipate the binding conformation of the DMTAB ligand with the relevant target proteins, specifically the ovarian cancer target (Rad6 ubiquitin-conjugated enzyme [PDB ID: 2YB6]) and breast cancer target (protein kinase CK2 [PDB ID: 6HNY].

Replacing Pyridine with Pyrazine in Molecular Cobalt Catalysts: Effects on Electrochemical Properties and Aqueous H2 Generation

Four new molecular Co(II)tetrapyridyl complexes were synthesized and evaluated for their activity as catalysts for proton reduction in aqueous environments. The pyridine groups around the macrocycle were substituted for either one or two pyrazine groups. Single crystal X-ray analysis shows that the pyrazine groups have minimal impact on the Co(II)–N bond lengths and molecular geometry in general. X-band EPR spectroscopy confirms the Co(II) oxidation state and the electronic environment of the Co(II) center are only very slightly perturbed by the substitution of pyrazine groups around the macrocycle. The substitution of pyrazine groups has a substantial impact on the observed metal- and ligand-centered reduction potentials as well as the overall H2 catalytic activity in a multimolecular system using the [Ru(2,2′-bipyridine)3]Cl2 photosensitizer and ascorbic acid as a sacrificial electron donor. The results reveal interesting trends between the H2 catalytic activity for each catalyst and the driving force for electron transfer between either the reduced photosensitizer to catalyst step or the catalyst to proton reduction step. The work presented here showcases how even the difference of a single atom in a molecular catalyst can have an important impact on activity and suggests a pathway to optimize the photocatalytic activity and stability of molecular systems.

Structural features of cubic “polyhedra” up to 24 vertices with four-, five- and six-sided faces

We present a complete list of three-dimensional structures corresponding to all cubic polyhedral graphs with the number of vertices up to 24, which have only square, pentagonal and hexagonal cycles. It can be considered as an Atlas of possible small- and middle-sized cages of three-dimensional 4-coordinated frameworks. Adhering to graph-theoretical terminology, we use the term “polyhedron”. But, strictly speaking, most of the constructed three-dimensional figures are not polyhedra because their “faces” are not planar. In addition, many polyhedra are significantly different in shape from conventional fullerenes. The spiral codes are used as the main topological identifier of the polyhedra. Three-dimensional coordinates of polyhedra are calculated by minimizing the sum of the squared deviations of the edge lengths and distances between the second neighbors from the idealized values. It is concluded that the minimum value of this sum can be considered as a new supplementary identifier of polyhedra and as a measure of deviation of the polyhedral structure from the set of true face-regular polyhedra. An algorithm for constructing polyhedral structures with edges of the same length is proposed. Also, we discuss the geometric properties of the constructed polyhedra and their relation to the stability of molecular systems.

Manipulation of molecules with electromagnetic fields

The goal of the present article is to review the major developments that have led to the current understanding of molecule–field interactions and experimental methods for manipulating molecules with electromagnetic fields. Molecule–field interactions are at the core of several, seemingly distinct areas of molecular physics. This is reflected in the organisation of this article, which includes sections on field control of molecular beams, external field traps for cold molecules, control of molecular orientation and molecular alignment, manipulation of molecules by non-conservative forces, ultracold molecules and ultracold chemistry, controlled many-body phenomena, entanglement of molecules and dipole arrays, and stability of molecular systems in high-frequency super-intense laser fields. The article contains 852 references.

Density functional theory: Non-Born–Oppenheimer Legendre transforms and Maxwell relations, equilibrium and stability conditions

The Legendre-transformed representations of the non-Born–Oppenheimer (NBO) density functional theory are analyzed and the corresponding Maxwell relations are derived. These relations exhibit various couplings between parameters of the NBO ground-state energy hypersurfaces: ε[{Ni, Zi, Mi}] and εφ[{Ni, Zi, Mi},φ], where Ni, Zi, and Mi denote, respectively, the number of particles i, their charge and mass, while φ stands for an external electric field. The criteria for intrinsic equilibrium and stability of molecular systems are formulated and discussed within both the BO and NBO approximations. The physical content of stability criteria is interpreted in terms of the Le Châtelier and the Le Châtelier–Braun principles. The classical nature of these criteria is revealed through the introduction of internal partial scalar pressures of the system components (groups of identical particles) within the local formulation of the theory. It is then shown that the criteria of equilibrium and stability in isolated molecular systems become the classical criteria of the ’’mechanical’’–electrostatic equilibrium and stability.