Theoretical Spectroscopic Study of Normal Raman and Charge Transfer Surface-Enhanced Raman Scattering (SERS) Spectra of the Adsorbed l- and d-Cysteine on the Chiral Au and Ag@Au Nanoclusters: Chirality Discrimination.

In this work, the discrimination of the enantiomers of cysteine (l- and d-CYS) using the chiral Au and Ag@Au clusters was theoretically investigated in the gas phase and water. Two modes were considered for the interaction of each enantiomer with the clusters (via only its S atom or its S atom and NH group, simultaneously). The interaction energy () and adsorption energy () for the complexation of each enantiomer with the clusters for each interaction mode were calculated.

Bonding in the high spin lithium clusters: Non-nuclear attractors play a crucial role.

The bonding in lithium high-spin clusters contradicts the usual chemical bonding concept since there are no electron pairs between the atoms, and they are bound with parallel spin electrons. Quantum theory of atoms in molecules and interacting quantum atom analysis (IQA) were used to investigate the nature of bonding in the high-spin clusters. Our findings demonstrate that the non-nuclear attractors (NNAs) are an essential component of the high-spin lithium clusters and play a key role in keeping them stable.

Fluorine as a Lewis acid: A symmetry-adapted perturbation theory based on density functional theory and interacting quantum atoms study of noncovalent interactions in the NCF⋯NH complex.

Different computational methods are used to investigate the nature of interaction in the NCF⋯NH model complex, in which the fluorine atom acts as a Lewis acid and forms a noncovalent bond with the ammonia (Lewis base). Symmetry-adapted perturbation theory based on density functional theory (SAPT(DFT)) indicates that the noncovalent interaction in the NCF⋯NH complex is mainly electrostatics. However, dispersion and induction terms also play important roles.

Directionality of Halogen Bonds: An Interacting Quantum Atoms (IQA) and Relative Energy Gradient (REG) Study.

Interacting Quantum Atoms (IQA) and Interacting Quantum Fragments (IQF) analyses are used to study (X=Cl and Br) model complexes in order to determine the origin of halogen bond directionality. IQA allows for the calculation of intra- and interatomic classical and exchange-correlation energies, which can be used to determine the energetic nature of the changes that occur when deviating from the preferred halogen bond approach. The Relative Energy Gradient (REG) method is also applied to rank the IQA energies and reveal which energy contributions best describe the total behavior of the system.

A new fluorene derived Schiff-base as a dual selective fluorescent probe for Cu and CN.

A new fluorene based fluorogenic chemosensor, 2-[(9H-Fluoren-2-ylmethylene)-amino]-phenol (L), has been designed, synthesized, and characterized by CHN analyses and different spectroscopic methods. This turn-on fluorogenic chemosensor shows high selectivity and sensitivity toward Cu and CN with low detection limits of 1.54 × 10 M and 1.

Nature of intramolecular interactions of vitamin C in view of interacting quantum atoms: the role of hydrogen bond cooperativity on geometry.

The conformational analysis of six dihedral angles was calculated by second-order Moller-Plesset perturbation theory (MP2) with the correlation-consistent aug-cc-pVDZ basis set. The quantum theory of atoms in molecules (QTAIM) was applied to gain a description of the atoms and chemical bonds. A high content of hydroxyl groups in vitamin C's (VC) structure leads to a wide range of intramolecular interactions.

Comparison of halogen bonds in M-X⋯N contacts (M = C, Si, Ge and X = Cl, Br).

The halogen bonds (XB) formed between some Si-X- and Ge-X- (X is Cl and Br) containing molecules and NCH (as a Lewis base) have been investigated and compared with C-X⋯N halogen bond. Although, in all cases, the existence of a positive electrostatic potential (σ-hole) along the extension of M-X was responsible for halogen bond formation, multipole expansion of electrostatic potential reveals that these positive potentials originate from different atomic multipole moments. Indeed, in addition to the monopole moment of M atoms, the quadrupole moment of X in C-X molecules, the dipole moment of the halogen in Si-X molecules and both the dipole and quadrupole moments of X in Ge-X molecules are mainly responsible for the existence of the σ-hole along the extension of the M-X bond.

Does fluorine participate in halogen bonding?

When R is sufficiently electron withdrawing, the fluorine in the R-F molecules could interact with electron donors (e.g., ammonia) and form a noncovalent bond (F⋅⋅⋅N).

Hydrogen-hydrogen interaction in planar biphenyl: a theoretical study based on the interacting quantum atoms and Hirshfeld atomic energy partitioning methods.

The nature of H-H interaction between ortho-hydrogen atoms in planar biphenyl is investigated by two different atomic energy partitioning methods, namely fractional occupation iterative Hirshfeld (FOHI) and interacting quantum atoms (IQA), and compared with the traditional virial-based approach of quantum theory of atoms in molecules (QTAIM). In agreement with Bader's hypothesis of H-H bonding, partitioning the atomic energy into intra-atomic and interatomic terms reveals that there is a net attractive interaction between the ortho-hydrogens in the planar biphenyl. This falsifies the classical view of steric repulsion between the hydrogens.