Jiazhong Sun

Bio: Jiazhong Sun is an academic researcher from Yantai University. The author has contributed to research in topics: Halogen bond & Hydrogen bond. The author has an hindex of 13, co-authored 20 publications receiving 625 citations.

Cooperativity between the halogen bond and the hydrogen bond in H3N...XY...HF complexes (X, Y=F, Cl, Br).

Abstract: Ab initio calculations are used to provide information on H(3)N...XY...HF triads (X, Y=F, Cl, Br) each having a halogen bond and a hydrogen bond. The investigated triads include H(3)N...Br(2)-HF, H(3)N...Cl(2)...HF, H(3)N...BrCl...HF, H(3)N...BrF...HF, and H(3)N...ClF...HF. To understand the properties of the systems better, the corresponding dyads are also investigated. Molecular geometries, binding energies, and infrared spectra of monomers, dyads, and triads are studied at the MP2 level of theory with the 6-311++G(d,p) basis set. Because the primary aim of this study is to examine cooperative effects, particular attention is given to parameters such as cooperative energies, many-body interaction energies, and cooperativity factors. The cooperative energy ranges from -1.45 to -4.64 kcal mol(-1), the three-body interaction energy from -2.17 to -6.71 kcal mol(-1), and the cooperativity factor from 1.27 to 4.35. These results indicate significant cooperativity between the halogen and hydrogen bonds in these complexes. This cooperativity is much greater than that between hydrogen bonds. The effect of a halogen bond on a hydrogen bond is more pronounced than that of a hydrogen bond on a halogen bond.

Competition between hydrogen bond and halogen bond in complexes of formaldehyde with hypohalous acids

Abstract: An ab initio study of the complexes formed by hypohalous acids (HOX, X = F, Cl and Br) with formaldehyde has been carried out at the MP2/aug-cc-pVTZ computational level. Two minima complexes are found, one with an H⋯O contact and the other one with an X⋯O contact. The former is more stable than the latter, and the strength difference between them decreases as the size of the X atom increases. The associated HO and XO bonds undergo a bond lengthening and red shift, whereas a blue shift was observed in the bond of the hypohalous acid not involved in the interaction. The interaction strength and properties in both complexes are analyzed with atoms in molecules (AIM) and natural bond orbital (NBO) theories. The energy decomposition analyses indicate that the contribution from the electrostatic interaction energy is larger in the hydrogen-bonded complexes than that in the halogen-bonded complexes.

Some measures for making halogen bonds stronger than hydrogen bonds in H2CS-HOX (X = F, Cl, and Br) complexes.

Abstract: The properties and applications of halogen bonds are dependent greatly on their strength. In this paper, we suggested some measures for enhancing the strength of the halogen bond relative to the hydrogen bond in the H2CS–HOX (X = F, Cl, and Br) system by means of quantum chemical calculations. It has been shown that with comparison to H2CO, the S electron donor in H2CS results in a smaller difference in strength for the Cl halogen bond and the corresponding hydrogen bond, and the Br halogen bond is even stronger than the hydrogen bond. The Li atom in LiHCS and methyl group in MeHCS cause an increase in the strength of halogen bonding and hydrogen bonding, but the former makes the halogen bond stronger and the latter makes the hydrogen bond stronger. In solvents, the halogen bond in the Br system is strong enough to compete with the hydrogen bond. The interaction nature and properties in these complexes have been analyzed with the natural bond orbital theory.

Prediction and characterization of the HMgH⋯LiX (X = H, OH, F, CCH, CN, and NC) complexes: a lithium–hydride lithium bond

Abstract: In the present paper, a new type of lithium bonding complex HMgH⋯LiX (X = H, OH, F, CCH, CN, and NC) has been predicted and characterized. Their geometries (C∞v) with all real harmonic vibrational frequencies were obtained using the second-order Moller–Plesset perturbation theory (MP2) with 6-311++G(d,p) basis set. For each HMgH⋯LiX complex, a lithium bond is formed between the negatively charged H atom of an HMgH molecule and the positively charged Li atom of an LiX molecule. Due to the formation of the complexes, the Mg–H and Li–H bonds are elongated. Interestingly, the Li–X harmonic vibrational stretching frequency is blueshifted in the HMgH⋯LiX (Y = CCH, CN, and NC) complexes and redshifted in the HMgH⋯LiX (X = H, OH, and F) complexes. The binding energy of this type of lithium bond ranges from 12.18 to 15.96 kcal mol−1, depending on the chemical environment of the lithium. The nature of lithium–hydride lithium bond has also been analyzed with natural bond orbital (NBO) and atoms in molecules (AIM).

Ab initio study of lithium-bonded complexes with carbene as an electron donor.

Abstract: The complexes H 2 C-LiX (X = H, OH, F, Cl, Br, CN, NC, CH 3 , C 2 H 3 , C 2 H, NH 2 ) have been studied with quantum chemical calculations at the MP2/6-31 1++G(d,p) level. A new type of lithium bond was proposed, in which the carbene acts as the electron donor. This new type of lithium bond was characterized in view of the geometrical, spectral and energetic parameters. The Li—X bond elongates in all lithium bonded complexes. The Li—X stretch vibration has a red shift in the complexes H 2 C-LiX (X = H, OH, F); however, it exhibits a blue shift in the complexes H 2 C-LiX (X = Cl, Br, CN, NC, CH 3 , C 2 H 3 , C 2 H, NH 2 ). The binding energies are in a range of 16.88—21.13 kcal/mol, indicating that the carbene is a good electron donor in the interaction. The energy decomposition analyses show that the electrostatic contribution is largest, polarization counterpart is followed, and charge transfer is smallest. The effect of substitution and hybridization on this type of lithium bond has also been investigated.

Halogen bonding and other σ-hole interactions: a perspective

Abstract: A σ-hole bond is a noncovalent interaction between a covalently-bonded atom of Groups IV–VII and a negative site, e.g. a lone pair of a Lewis base or an anion. It involves a region of positive electrostatic potential, labeled a σ-hole, on the extension of one of the covalent bonds to the atom. The σ-hole is due to the anisotropy of the atom's charge distribution. Halogen bonding is a subset of σ-hole interactions. Their features and properties can be fully explained in terms of electrostatics and polarization plus dispersion. The strengths of the interactions generally correlate well with the magnitudes of the positive and negative electrostatic potentials of the σ-hole and the negative site. In certain instances, however, polarizabilities must be taken into account explicitly, as the polarization of the negative site reaches a level that can be viewed as a degree of dative sharing (coordinate covalence). In the gas phase, σ-hole interactions with neutral bases are often thermodynamically unfavorable due to the relatively large entropy loss upon complex formation.

Halogen Bonding: An Interim Discussion

Abstract: Halogen bonding is a noncovalent interaction that is receiving rapidly increasing attention because of its significance in biological systems and its importance in the design of new materials in a variety of areas, for example, electronics, nonlinear optical activity, and pharmaceuticals. The interactions can be understood in terms of electrostatics/polarization and dispersion; they involve a region of positive electrostatic potential on a covalently bonded halogen and a negative site, such as the lone pair of a Lewis base. The positive potential, labeled a σ hole, is on the extension of the covalent bond to the halogen, which accounts for the characteristic near-linearity of halogen bonding. In many instances, the lateral sides of the halogen have negative electrostatic potentials, allowing it to also interact favorably with positive sites. In this discussion, after looking at some of the experimental observations of halogen bonding, we address the origins of σ holes, the factors that govern the magnitudes of their electrostatic potentials, and the properties of the resulting complexes with negative sites. The relationship of halogen and hydrogen bonding is examined. We also point out that σ-hole interactions are not limited to halogens, but can also involve covalently bonded atoms of Groups IV-VI. Examples of applications in biological/medicinal chemistry and in crystal engineering are mentioned, taking note that halogen bonding can be "tuned" to fit various requirements, that is, strength of interaction, steric factors, and so forth.

Halogen bonding--a novel interaction for rational drug design?

Abstract: Although recognized in small molecules for quite some time, the implications of halogen bonding in biomolecular systems are only now coming to light. In this study, several systems of proteins in complex with halogenated ligands have been investigated by using a two-layer QM/MM ONIOM methodology. In all cases, the halogen−oxygen distances are shown to be much less than the van der Waals radius sums. Single-point energy calculations unveil that the interaction becomes comparable in magnitude to classical hydrogen bonding. Furthermore, we found that the strength of the interactions attenuates in the order H ≈ I > Br > Cl. These results agree well with the characteristics discovered within small model halogen-bonded systems. A detailed analysis of the interactions reveals that halogen bonding interactions are responsible for the different conformation of the molecules in the active site. This study would help to establish such interaction as a potential and effective tool in the context of drug design.