卤代对苝醌类光敏剂光敏活性影响的量子化学研究

以一种新型的醌类光敏剂—菌生素 (HMB)为模型化合物 ,利用量子化学从头算HF/ 6 31G和含时密度泛函TD B3LYP/ 6 31G方法计算研究了卤代作用对醌类光敏剂分子性质和光敏活性的影响 .结果发现 ,卤代作用降低了HMB母体的HOMO和LUMO能级 (EHOMO和ELUMO)及其差值△E ,随卤族元素从上到下 ,EHOMO和ELUMO呈增大趋势 ,而△E呈减小趋势 ,使得分子激发光谱有不同程度的红移 ,在增加PQP三重态量子产率的同时降低了分子最低三重激发态的能量 ,两种作用相互抵消 ,使得卤代物的 1O2 量子产率与母体相似 ;增加了分子的绝热电子亲合势 ,使分子产生O2 -的能力下降 ;卤原子的引入 ,降低了HMB母体分子内氢键的强度 ,同时使顺式构型的分子内质子传递势垒增大 ,而使反式构型势垒减小 .     

Comparison of the effective core potential and model potential methods in studies of electron correlation energy in molecules: Dihalides and halogen hydrides

Summary The effective core potential and model potential methods were used in post-SCF calculations on HC1, HBr, Cl₂, and Br₂ in order to gain insight into the effect of insufficient representation of inner nodes in the valence orbitals of the approximate methods. The results show that while the correlation energy may be slightly overestimated (by 1–7%), both the electric moment functions and the quantities depending on energy differences are consistently similar for the methods studied and close to the results from all-electron calculations.Dedicated to Prof. Klaus Ruedenberg     

Theoretical study on intermolecular interactions in BrF/HnX adducts

Equilibrium geometries, interaction energies, and charge transfer for the intermolecular interactions between BrF and H_nX (HF, H₂O, and NH₃) were studied at the MP2/6-311++G(3d,3p) level. The halogen-bonded geometry and hydrogen-bonded geometry are observed in these interactions. The calculated interaction energies show that the halogen-bonded structures are more stable than the corresponding hydrogen-bonded structures. To study the nature of the intermolecular interactions, symmetry-adapted perturbation theory (SAPT) calculations were carried out and the results indicate that the halogen bonding interactions are dominantly inductive energy in nature, while electrostatic energy governs the hydrogen bonding interactions.     

Silver (I)-promoted asymmetric halohydrin reaction of chiral N-enoyl-2-oxazolidinones: scope and limitations

The halohydrin reaction of chiral N-enoyl-2-oxazolidinones 1 by halogen (Br₂/I₂) and water were efficiently carried out in aqueous organic solvent promoted by silver(I) with high anti- and regioselectivity and moderate to good diastereoselectivities. The alkenoyl, cinnamoyl and electron-deficient cinnamoyl substrates smoothly underwent bromohydrin reaction in aqueous acetone but no iodohydrin reaction, where as electron-rich cinnamoyl substrates preferred to undergo iodohydrin reaction in aqueous acetone with moderate diastereoselectivity and enhanced diastereoselectivity was observed in aqueous THF.     

Halogen bonding-driven formation of supramolecular macrocycles and double helix

Halogen bonding has been used to hold two hydrogen bonded aromatic amide foldamers to form supramolecular macrocycles.     

Programmable and Self-Healable Liquid Crystal Elastomer Actuators Based on Halogen Bonding

Shape-changing polymeric materials have gained significant attention in the field of bioinspired soft robotics. However, challenges remain in versatilizing the shape-morphing process to suit different tasks and environments, and in designing systems that combine reversible actuation and self-healing ability. Here, we report halogen-bonded liquid crystal elastomers (LCEs) that can be arbitrarily shape-programmed and that self-heal under mild thermal or photothermal stimulation. We incorporate halogen-bond-donating diiodotetrafluorobenzene molecules as dynamic supramolecular crosslinks into the LCEs and show that these relatively weak crosslinks are pertinent for their mechanical programming and self-healing. Utilizing the halogen-bonded LCEs, we demonstrate proof-of-concept soft robotic motions such as crawling and rolling with programmed velocities. Our results showcase halogen bonding as a promising, yet unexplored tool for the preparation of smart supramolecular constructs for the development of advanced soft actuators.     

One‐Pot Synthesis of Pyrazole‐5(3)‐carboxyamides

Abstract

A convenient one‐pot synthesis of eight pyrazole‐5(3)‐carboxyamides from the reaction of the 5(3)‐trichloromethylpyrazoles with amines, in good yield, is reported. These reactions show that the trichloromethyl group is a convenient precursor to carboxyamide groups.     

New Look into the Synthesis of Polyhalogenoarylphosphanes

The present study shows new aspects of the synthesis of polyhalogenoarylphosphanes. The sterically hindered anions Ph(R)P-Y^? (1a–c, Y = O, lone pair; R = Ph, Bu^t) have been used to show the complexity of the reaction between phosphorus nucleophiles and hexahalogenobenzenes or 9-bromofluorene (E3). The Ph(Bu^t)P-O^? (1a) anion reacts with hexachlorobenzene (E1), hexafluorobenzene (E2), or E3 to give Ph(R)P(O)X (4a–c, X = F, Cl, Br) with the release of the corresponding carbanion as a nucleofuge, followed by side reactions. In contrast, the lithium phosphides Ph(R)PLi (1b,c) react with hexahalogenobenzenes to give the corresponding diphosphanes 5a,b as the main product and traces of P-arylated products, i.e., Ph(R)P-C₆X₅ (10a,b, X = Cl, F). Unexpectedly, Ph(Bu^t)PLi (1b) reacts with an excess of 9-bromofluorene to give only halogenophosphane Ph(Bu^t)P-X.     

卤键在化学传感和分子识别中的应用

卤键是一种新的分子间非共价作用力,它存在于卤素原子(路易斯酸)和具有孤电子对的原子或π-电子体系(路易斯碱)之间,在超分子化学、材料科学、生物识别和药物设计等领域已经显示出独特的优势。本文主要从卤键的特征和在化学传感和分子识别中的应用以及发展前景等几方面进行了介绍,期望引起人们对卤键的更多关注。