发光性受体的分子设计与分子识别

介绍了发光受体的几种典型分子识别模型。从分子识别与超分子化学的角度综述了它们在分子离子识别中的应用。对近几年发展较快的分子印迹技术及其应用进行了综述。引用文献71篇。     

冠醚的分子设计及其识别性质研究进展

综述了冠醚化学研究的最新进展：包括低对称冠醚、臂式冠醚、双冠醚等的分 子设计和离子键合、离子识别的热力学起源和分子组装的研究进展。     

聚苯并噁嗪高性能化:分子设计、合金与纳米复合物

聚苯并噁嗪通过环状苯并噁嗪单体热诱导开环聚合得到,作为一种新型的酚醛树脂,不仅具有传统酚醛树脂的耐热、低吸水性等性质,还具有传统酚醛树脂不具备的性能,如分子设计的灵活性、固化反应没有小分子副产物产生、优异的尺寸稳定性以及良好的阻燃性能,在微电子、印刷电路板、电子封装以及航空航天等高技术领域具有广阔的应用前景.然而,聚苯并噁嗪缺点是固化温度高、固化材料脆性大.本文介绍了聚苯并噁嗪性能增强的各种方法,包括新型单体分子设计、引入可交联单元、高相对分子质量聚合物前体制备、聚合物合金化、纳米复合等.最近,石墨烯和笼型聚倍半硅氧烷(POSS)与聚苯并噁嗪复合材料因具有优异的热性能和电学性能,成为先进电子材料的潜力材料.     

Fine-tuning ligand-receptor design for selective molecular recognition of dicarboxylic acids

The host-guest interaction between the hexaaza macrocyclic ligand 3,7,11,18,22,26-hexaazatricyclo[26.2.2.2]tetratriaconta-1(31),13(34),14,16(33),28(32),29-hexaene (P3) and three rigid dicarboxylic acids (isophthalic acid, H2is; phthtalic acid, H2ph; and terephthalic acid, H2te) has been investigated using potentiometric equilibrium methods and NMR spectroscopy including the measurement of intermolecular nuclear Overhauser effects (NOEs) and self-diffusion coefficients (D). Ternary complexes are formed in aqueous solution as a result of hydrogen bond formation and Coulombic interactions between the host and the guest. In the [(H6P3)(is)]4+ complex, those bonding interactions reach a maximum yielding a log K6R of 4.74. Competitive distribution diagrams and total species distribution diagrams are used to illustrate the main features of these systems. In particular, a selectivity of over 89% at p[H] = 5.0 is obtained for the complexation of the is versus the te substrates. The recognition capacity of P3 over dicarboxylic acids (da) is compared to the related hexaaza macrocycle Me2P3 (7,22-dimethyl-3,7,11,18,22,26-hexaazatricyclo[26.2.2.2]tetratriaconta-1(30),13,15,28,31,33-hexaene) that binds da with a lesser strength, and it is not selective. Theoretical calculations performed at molecular dynamics level have also been carried out and point out that the origin of selectivity is mainly due to the capacity of the P3 ligand receptor to adapt to the geometry of the dicarboxylic acid to form relatively strong hydrogen bonds.     

Towards the design of neutral molecular tweezers for anion recognition

Molecular tweezers are simple molecular receptors that can be characterized by the presence of two flat pincers separated by a more or less rigid tether. They have the ability to form complexes with a substrate molecule by gripping the substrate between the tips of the tweezers in a similar manner to that of mechanical tweezers. Kl?rner et al. synthesized one of the structurally simplest molecular tweezers, which is reported to bind electrodeficient aromatic and aliphatic substrates as well as organic cations. Complexes between these molecular tweezers and electron-rich aromatic, aliphatic, or anionic substrates have not been observed. Inspired by several recent reports that describe the interaction of hexafluorobenzene with electron-rich sites of molecules, we conducted a theoretical study to show the possibility of building molecular tweezers, based on those synthesized by Kl?rner, which were able to bind to anions and thus increase their potential as molecular receptors. We characterized complexes formed between several fluorinated derivatives of simple tweezers and an iodine anion, and analyzed the nature of the intermolecular interactions as well as the energetics for the process of complexation. The stabilization trend reflected by the energetic results when fluorine substituents were added to benzene rings confirms our hypothesis about the possibility of obtaining neutral tweezers composed of aromatic rings that can bind anions.     

Nanoparticles: scaffolds for molecular recognition

Monolayer and mixed-monolayer protected clusters (MPCs and MMPCs) have great potential to combine molecular functionality with the intrinsic properties of nanometer-sized scaffolds. This synergy can be used to create complex functional devices, including redox-active, electronic, or magnetic storage devices, solution-based sensors, and highly efficient catalysts. This review outlines some of the recent developments in nanoscale receptors based on synthetic and nonbiological recognition elements. In these nanoparticle systems, molecular recognition is achieved by covalent attachment of receptors on the nanoparticles coupled with noncovalent interactions to target substrates. Synthetic host-guest systems, hydrogen bonding, change in redox states, pi-pi stacking, rotaxane formation, and ion recognition are the main topics covered in this review.     

Molecular tectonics: from molecular recognition of anions to molecular networks

One may apply concepts developed in the context of molecular recognition of anions by synthetic receptors in solution to the design of molecular tectons capable of generating molecular networks with anionic species in the crystalline phase. With respect to that, bis-cyclic amidinium dications are interesting tectons because they offer two positive charges allowing strong electrostatic charge–charge interactions with anions and four acidic protons divergently oriented and capable of forming two sets of two H-bond chelates. The latter characteristic is of interest for the generation of supramolecular chirality taking place within the second coordination sphere around anionic metal complexes adopting an octahedral coordination geometry.     

High throughput synthesis of ester library utilizing selective molecular reactivity and recognition technology

This paper reports a new solid support reagent that showed high degrees of selective molecular reactivity and molecular recognition in homo-functional reactions (reactions having similar reactive functionality in reactants and products).     

High alpha/beta-anomer selectivity in molecular recognition of carbohydrates by artificial receptors

[structure: see text] New effective, acyclic, pyridine-based receptors 1-3 show remarkable alpha/beta binding selectivity in the recognition of monosaccharides. They are able to participate in cooperative and bidentate hydrogen bonds with sugar hydroxyls as well as in CH-pi interactions with CH's of sugar molecules.     

Chromene "lock", thiol "key", and mercury(II) ion "hand": a single molecular machine recognition system

A regenerative, molecular machine-like "ON-OFF-ON" chemosensor based on a chromene molecule with the pyran ring "OFF-ON-OFF" cycle is reported for the first time. It behaves as a molecular lock that requires a thiol "key" to open the lock and a mercury(II) ion "hand" that unlatches the key for unsheathing the key to close the lock.     

Directed molecular recognition: design and synthesis of neutral receptors for biotin to bind both its functional groups

The neutral receptors 1 and 2 are designed and synthesized for the recognition of biotin, a biologically significant molecule, in chloroform to bind completely both of its functional groups simultaneously, i.e., cyclic urea and the carboxyl groups. The truncated receptor 3 binds only the cyclic urea moiety.     

Structural biology of the cell adhesion protein CD2: from molecular recognition to protein folding and design

CD2 (cluster of differentiation 2) is a cell adhesion molecule expressed on T cells and is recognized as a target for CD48 (rats) and CD58 (humans). Tremendous progress has been achieved in understanding the function of CD2, the mechanism of molecular recognition and protein folding, thus, leading towards the use of this protein as a scaffold for protein design. CD2 has been shown to set quantitative thresholds in T cell activation both in vivo and in vitro. Further, intracellular CD2 signaling pathways and networks are being discovered by the identification of several cytosolic tail binding proteins. In addition, a new method for directly measuring heterophilic adhesion has been developed. The functional "hot spot" for the adhesion surface of CD2 and CD58 has been dissected. Detailed NMR studies reveal that rat CD2 weakly self-associates to form a homodimeric structure in solution. Dynamic interaction of CD2 with the GYF and SH3 domains has been investigated. CD2 has been shown to form fibrils in the presence of 2,2,2-trifluoroethanol (TFE) and at low pH. Furthermore, kinetic studies have been completed to monitor the effect of surface hydrophobic residues and intramolecular bridges on the folding pathways of CD2. Our lab has de novo designed single calcium-binding sites into domain 1 of rat CD2 (CD2-D1) with strong metal selectivity. In addition, the EF-hand motifs have been grafted into CD2 to understand the site-specific calcium-binding affinity of calmodulin and calcium-dependent cell adhesion.     

Complexity in molecular recognition

The anomer selectivity of artificial carbohydrate receptors was studied using in silico methods in order to shed light on the thermodynamic driving forces at work during molecular recognition in general. The contributions of relevant intermolecular hydrogen bonds were investigated by means of generalized compliance constants in order to dissect important from less important non-covalent interactions. Even at this moderately low rung on the ladder of complexity essential aspects of molecular recognition are not explainable in terms of additive intermolecular interactions. Though molecular recognition seems to be a complex and emergent property, a rationale for the diastereoselectivity of carbohydrate receptors was obtained by a combination of experimental data, free energy simulations and ab initio calculations.     

Theoretical studies in molecular recognition: Rebek's cleft

Molecular recognition in Rebek's cleft was studied with the MM2 force field. A new computational protocol was used to determine the free energies of substrate binding to this topologically unique model receptor. The energies and structural features of substrate-receptor complexes reveal that molecular recognition involves ammonium ion binding to the interior of the cleft and aromatic π-stacking on the exterior of the cleft.     

Forces in molecular recognition: Comparison of experimental data and molecular mechanics calculations

Summary NMR studies of the rotation barrier of the disaccharide of the glycopeptide antibiotic vancomycin have been used to test the performance of computer simulation techniques using molecular mechanics. In the absence of any solvated water, no correlation could be found between experiment and calculation. By introducing solvent water molecules into the binding region of the antibiotic, the NMR results could be simulated both qualitatively and quantitatively within experimental error without using massive computational resources.     

ALADDIN: An integrated tool for computer-assisted molecular design and pharmacophore recognition from geometric,steric, and substructure searching of three-dimensional molecular structures

Summary ALADDIN is a computer program for the design or recognition of compounds that meet geometric, steric, and substructural criteria. ALADDIN searches a database of three-dimensional structures, marks atoms that meet substructural criteria, evaluates geometric criteria, and prepares a number of files that are input for molecular modification and coordinate generation as well as for molecular graphics. Properties calculated from the three-dimensional structure are described by either properties calculated from the molecule itself or from the molecule as compared to a reference molecule and associated surfaces. ALADDIN was used to design analogues to probe a bioactive conformation of a small molecule and a peptide, to test alternative superposition rules for receptor mapping of the D2 dopamine receptor, to recognize unexpected D2 dopamine agonist activity of existing compounds, and to design compounds to fit a binding site on a protein of known structure. We have found that series designed by ALADDIN show much more subtle variation in shape than do those designed by traditional methods and that compounds can be designed to be very close matches to the objective.     

Squaramido-based receptors: applicability of molecular interaction potential to molecular recognition of polyalkylammonium compounds

 A computational study of the mechanism of host–guest complexation between quaternary ammonium compounds and squaramido-based tripodal receptors has been carried out. Semiempirical molecular orbital calculations, which are in qualitative agreement with experimental results have been performed using the PM3 Hamiltonian. Molecular interaction potential (MIP) maps were used to analyze the suitability of both host and guest binding units for a high-affinity recognition process. MIP calculations were computed from PM3 wavefunctions of the corresponding ammonium cations and dimethyl squaramide as a model compound for the hydrogen-bond-acceptor unit of the receptors. MIP analyses are helpful for understanding the host–guest process from the point of view of the double-complementarity principle. Received: 23 June 1999 / Accepted: 22 September 1999 / Published online: 17 January 2000