Recent advances in the study of biomolecular interactions by capillary electrophoresisCapillary electrophoresis (CE) has been abundantly used in the study of molecular interactions owing to such advantages as short analysis time, low sample size requirement, high separation efficiency, and flexible applications. The focus of this paper is to review recent studies and advances (mainly from 1998 to now) in biomolecular interactions using CE. Five CE modes: zone migration CE, affinity CE, frontal analysis (FA), Hummel-Dreyer (HD) and vacancy peak (VP) are cited and compared. Quantitative aspects of the thermodynamics and kinetics of biomolecular interaction are reviewed. Several biomolecular binding systems, including protein-protein (polypeptide), protein-DNA (RNA), protein(polypeptide)-carbohydrate, protein-small molecule, DNAsmall molecule, small molecule-small molecule, have been well characterized by CE. CE is shown to be a powerful tool for the determination of the binding parameters of various bioaffinity interactions.

Inorganic benzene-like compounds such as boroxine and borazine are of interest in chemistry. Here we report on theoretical prediction of a new member of the inorganic benzene family: boronyl boroxine. This perfectly planar D3h B6O6 (1, (1)A1') cluster is identified as the global minimum of the system at density functional theory (B3LYP) and molecular orbital theory levels, which lies at least ∼20 kcal∕mol lower in energy than alternative structures. It can be formulated as B3O3(BO)3 and features a boroxol B3O3 ring as the core with three boronyl (BO) groups attached terminally, closely resembling boroxine and obtainable from the latter via isovalent BO∕H substitution. Detailed bonding analyses reveal weak π aromaticity in boronyl boroxine, rendering it a true analog to boroxine and borazine. Upon electron attachment, the slightly distorted C2v B6O6(-) (2, (2)A2) anion is also perfectly planar, and its electronic properties are calculated. A huge energy gap (4.83 eV) is predicted for B6O6(-) (2) at B3LYP level, which is characteristic of a stable closed-shell neutral cluster. Similar to benzene, boronyl boroxine is also predicted to be an effective inorganic ligand to form sandwich-type complexes, such as D3d [B3O3(BO)3]2Cr (4, (1)Ag).

Based upon comprehensive theoretical investigations and known experimental observations, we predict the existence of the double-chain planar D(2h) B(4)H(2)(1), C(2h) B(8)H(2)(3), and C(2h) B(12)H(2)(5) which appear to be the lowest-lying isomers of the systems at the density functional theory level. These conjugated aromatic borenes turn out to be the boron hydride analogues of the conjugated ethylene D(2h) C(2)H(4)(2), 1,3-butadiene C(2h) C(4)H(6)(4), and 1,3,5-hexatriene C(2h) C(6)H(8)(6), respectively, indicating that a B(4) rhombus in B(2n)H(2) borenes (n = 2, 4, 6) is equivalent to a C=C double bond unit in the corresponding C(n)H(n+2) hydrocarbons. Detailed canonical molecular orbital (CMO), adaptive natural density partitioning (AdNDP), and electron localization function (ELF) analyses unravel the bonding patterns of these novel borene clusters and indicate that they are all overall aromatic in nature with the formation of islands of both σ- and π- aromaticity. The double-chain planar or quasi-planar C(2v) B(3)H(2)(-)(7), C(2) B(5)H(2)(-)(8), and C(2h) B(6)H(2)(9) with one delocalized π orbital, C(2v) B(7)H(2)(-)(10), C(2) B(9)H(2)(-)(11), and C(2h) B(10)H(2)(12) with two delocalized π orbitals, and C(2v) B(11)H(2)(-)(13) with three delocalized π orbitals are found to be analogous in π-bonding to D(2h) B(4)H(2)(1), C(2h) B(8)H(2)(3), and C(2h) B(12)H(2)(5), respectively. We also calculated the electron affinities and ionization potentials of the neutrals and simulated the photoelectron spectroscopic spectra of the monoanions to facilitate their future experimental characterization. The results obtained in this work enrich the analogous relationship between hydroborons and their hydrocarbon counterparts and help to understand the high stability of the theoretically predicted all-boron nanostructures which favor the formation of double-chain substructures.