官能团化刚性大环的超分子化学

重点介绍具有纳米尺寸的苯炔刚性大环的超分子化学: 包括聚集效应, 主客体化学、液晶行为及二维、三维超分子结构等.     

Characterization and Crystal Structure of a New Holmium（Ⅲ） Complex with the Macrocyclic Ligand Derived from 2,6-Diformyl-4-methylphenol and Diethylenetriamine

The title compound （13,27-dimethyl-3,6,9,17,20,23-hexaazatricyclo-[23.3.1.1^11.15]- triaconta-l（29）,2,9,11,13,15（30）,16,23,25,27-decaene-29,30-diol-N^3,N^6,N^9,O^29,O^30）-bis（nitrato-O,O＇）- holmium（m） nitrate hydrate has been prepared and characterized by elemental analysis, infrared spectra, and electrospray mass spectra. Its crystal and molecular structures were determined by X-ray diffraction methods. The crystal crystallizes in the monoclinic system, space group C2/c with a = 23.737（12）, b = 14.237（7）, c = 19.801（10） A, β = 91.36（1）^o, Mr = 831.57, V = 6690（6） A^3, Z = 8, Dc = 1.651 g/cm^3, F（000） = 3344, R = 0.0482 and wR = 0.0923. The holmium ion is located in one of the compartments of the macrocyclic ligand and presents a distorted tricapped trigonal prismatic coordination geometry. The macrocycle is coordinated with two oxygen and three nitrogen atoms. Two nitrates are chelated in the opposite positions of the macrocycle, and the third one is ionic.     

Solid state and solution structures of the lanthanide complexes with cryptand (2.2.1): Crystallographic and NMR studies of a dimeric praseodymium (2.2.1) cryptate containing two μ-hydroxo bridges

A dimeric lanthanide cryptate was obtained by the addition of an excess of cryptand (2.2.1) to a slightly hydrated solution of the monomeric praseodymium (2.2.1) perchlorate complex in acetonitrile. This new lanthanide compound is centrosymmetric and displays the space groupP2₁/n. The encryptated metal ions are nine-coordinated, they are bonded to all the heteroatoms of a (2.2.1) ligand and they are linked to each other by two -hydroxo bridges. The hydroxyl groups are relegating the cryptands to both end of the dimer and the praseodymium ions are less effectively accomodated in the macrocylic internal cavities than in the case of the monomeric Pr(2.2.1) complex. The formation of both the monomeric and the dimeric lanthanide complexes is readily observed by proton NMR. Supplementary data relevant to this article are deposited with the British Library Lending Division as Supplementary Publication No. 82050 (24 pages).Presented at the Fourth International Symposium on Inclusion Phenomena and the Third International Symposium on Cyclodextrins, Lancaster, U.K., 20–25 July 1986.     

Employing Imine Macrocycle Ligand in the Atom Transfer Radical Polymerization of Methyl Methacrylate

Imine macrocycle M₁ was successfully used in conjunction with CuBr as a catalytic system in the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). The role of the reaction conditions was clearly observed. Such reaction conditions were found to be the molar ratios of the reactants, the chosen initiating systems, and some additional ambient conditions (e.g. temperature, solvent). MMA homopolymers were successively prepared via ATRP by using benzhydrylbromide, diethylmethylbromomalonate initiating systems under the appropriate reaction conditions. Definite well‐known structures of the formed polymers were unambiguously identified with ¹H NMR.     

Molecule‐Induced Peroxide Homolysis

The homolytic cleavage of peroxide bonds, leading to the formation of free radicals, plays an important role in the (spontaneous) oxidation of a wide variety of hydrocarbons in the presence of oxygen. Such aerobic oxidations can be desired (e.g. for industrially applied autoxidations) or undesired (e.g. food deterioration). In this contribution we provide experimental and computational evidence for a molecule‐induced homolytic dissociation mechanism between alkyl peroxide and compounds featuring weakly bonded H atoms such as (di)unsaturated hydrocarbons.     

Synthesis,structural characterization,EPR spectroscopy and Hirshfeld surface analysis of a novel Cu2+‐doped 3,14‐diethyl‐2,13‐diaza‐6,17‐diazoniatricyclo[16.4.0.07,12]docosane bis(perchlorate)

Cyclam derivatives and their metal complexes have been found to exhibit an anti‐HIV effect and stimulate the activity of stem cells from bone marrow. The strength of their binding to the CXCR4 receptor correlates with anti‐HIV and stem‐cell activities. Knowledge of the conformation and crystal packing of various macrocyclic metal complexes has become important in developing new effective anti‐HIV drugs. The synthesis and preparation of single crystals of a new Cu²⁺‐doped macrocyclic compound, (3,14‐diethyl‐2,6,13,17‐tetraazatricyclo[16.4.0.0^7,12]docosane)copper(II) bis(perchlorate)–3,14‐diethyl‐2,13‐diaza‐6,17‐diazoniatricyclo[16.4.0.0^7,12]docosane bis(perchlorate) (0.69/0.31), {[Cu(C₂₂H₄₄N₄)](ClO₄)₂}_0.69·(C₂₂H₄₆N₄²⁺·2ClO₄^?)_0.31, is reported. Characterization by X‐ray diffraction analysis shows that the asymmetric unit contains half of a centrosymmetric molecule. The macrocyclic ligand in the compound adopts the most stable trans‐III conformation. The Cu—N distances of 2.015 (3) and 2.047 (3) Å are normal, but the long axial Cu—O bond of 2.795 (3) Å may be due to a combination of the Jahn–Teller effect and the strong in‐plane ligand field. The crystal structure is stabilized by hydrogen bonding between secondary N—H groups, the N atoms of the macrocycle and the O atoms of the perchlorate anions. Hirshfeld surface analysis with 2D (two‐dimensional) fingerprint plots indicates that the main contributions to the crystal packing are from H…H (58.0%) and H…O/O…H (41.9%) interactions. Electron paramagnetic resonance (EPR) properties are also described.     

Removal of Organic Micropollutants from Water by Macrocycle-Containing Covalent Polymer Networks

Access to clean drinking water is a recognized societal need that touches on the health and livelihood of millions of people worldwide. This is providing an incentive to develop new water-treatment technologies. Traditional technologies, while widespread, are usually inefficient at removing organic pollutants from sewage or so-called grey water. Macrocycle-containing covalent polymer networks have begun to attract attention in the context of water treatment owing to the inherent stability provided by the polymer backbones and their ability to capture micropollutant guests as the result of tunable macrocycle-based host–guest interactions. In this Minireview, we summarize recent advances (from 2016 to mid-2020) involving the removal of organic micropollutants from water using macrocycle-containing covalent polymer networks. An overview of future challenges within this subfield is also provided.     

Accessing Improbable Foldamer Shapes with Strained Macrocycles

The alkylation of some secondary amide functions with a dimethoxybenzyl (DMB) group in oligomers of 8-amino-2-quinolinecarboxylic acid destabilizes the otherwise favored helical conformations, and allows for cyclization to take place. A cyclic hexamer and a cyclic heptamer were produced in this manner. After DMB removal, X-ray crystallography and NMR show that the macrocycles adopt strained conformations that would be improbable in noncyclic species. The high helix folding propensity of the main chain is partly expressed in these conformations, but it remains frustrated by macrocyclization. Despite being homomeric, the macrocycles possess inequivalent monomer units. Experimental and computational studies highlight specific fluxional pathways within these structures. Extensive simulated annealing molecular dynamics allow for the prediction of the conformations for larger macrocycles with up to sixteen monomers.     

Controlled ring‐expansion polymerization of thiiranes based on cyclic aromatic thiourethane initiator

Ring‐expansion polymerization (REP) of thiiranes was investigated using 3H‐benzothiazol‐2‐one (BT) as the cyclic aromatic thiourethane initiator in the presence of tetrabutylammonium chloride (TBAC) catalyst. The polymerization proceeded in a well‐controlled manner to afford cyclic polysulfides with one BT moiety per macrocycle, as confirmed by MALDI‐TOF MS spectroscopy. Differential scanning calorimetry (DSC) measurement of the obtained cyclic polysulfides revealed slight decrease in the glass‐transition temperature as the increase in the molecular weight, supporting the cyclic topology of the products. Postpolymerization of thiiranes using the BT‐initiated cyclic polysulfide as the macroinitiator afforded the ring‐expanded product while maintaining the narrow polydispersity and well‐defined cyclic structure, which enabled precise synthesis of cyclic block copolymer with different thiirane combination. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2442–2449     

Macrocyclic Donor-Acceptor Dyads Composed of Oligothiophene Half-Cycles and Perylene Bisimides

A series of donor-acceptor (D−A) macrocyclic dyads consisting of an electron-poor perylene bisimide (PBI) π-scaffold bridged with electron-rich α-oligothiophenes bearing four, five, six and seven thiophene units between the two phenyl-imide substituents has been synthesized and characterized by steady-state UV/Vis absorption and fluorescence spectroscopy, cyclic and differential pulse voltammetry as well as transient absorption spectroscopy. Tying the oligothiophene strands in a conformationally fixed macrocyclic arrangement leads to a more rigid π-scaffold with vibronic fine structure in the respective absorption spectra. Electrochemical analysis disclosed charged state properties in solution which are strongly dependent on the degree of rigidification within the individual macrocycle. Investigation of the excited state dynamics revealed an oligothiophene bridge size-dependent fast charge transfer process for the macrocyclic dyads upon PBI subunit excitation.