[2_3]Cyclophanes电子结构的理论研究

用改进的重叠模型多重散射X_α自洽场方法计算环芳类化合物[2_3]Cyclophanes的电子结构,分析该类分子中分子轨道通过空间和通过键的相互作用,单键连接桥、双键连接桥对通过键相互作用的影响,用过渡态理论方法计算分子前线分子轨道的电离能,理论结果与紫外光电子能谱符合较好.

Cyclophanes的合成进展

Cyclophanes是一类芳环通过烷基桥连接而成的大环化合物,是超分子化学中的受体,本文按全碳、含杂原子、笼形分类Cyclophanes,对其各类的合成进行综述。

Synthesis and Molecular Structures of Two Novel π-Conjugation Extended Dithia[3.3]metacyclophanes

Two novel dithia[3.3]metacyclophanes substituted with ethynyl groups were synthesized as small-sized metacyclophanes from the corresponding brominated dithia-metacyclophanes via C-C bond formation reaction. These compounds were characterized by using 1H NMR, mass spectrometry and elemental analyses. The exact structures were determined by using X-ray diffraction analyses. X-ray diffraction analysis results revealed that these compounds have anti conformations because of existence of intermolecular π-π interaction and some short contacts in the crystal. The long wavelength fluorescence was observed for one of the compound having a pyrene moiety in solid state because of the existence of the intermolecular π-π interaction between two pyrene units.

Synthesis and Guest-Binding Behavior of Water-Soluble Cyclophanes Bearing PEG Residues

A water-soluble cyclophane (1) having poly(ethylene glycol) (PEG) moieties has been prepared from a tetraazide-functionalized cyclophane derivative and four poly(ethylene glycol) methyl ether acetylenes by Cu(I)-catalyzed 1,3 dipolar cycloadditions (click chemistry). An analogous derivative having a pyrene moiety (2) was also prepared in a similar manner. The guest-binding behavior of 1 and 2 toward anionic guests such as 6-p-toluidinonaphthalene-2-sulfonate was investigated by fluorescence spectroscopy. The binding constants (K) of the host-guest complexes were evaluated.

Molecular recognition of cyclophanes in water

Molecular recognition in water,the biological solvent,always receives significant research focus in supramolecular chemistry.The mechanisms of molecular recognition in water is key to comprehending biological processes at the molecular level.Over the past five decades,supramolecular chemists have developed a vast array of synthetic receptors with highly diverse structures and recognition properties.Among them,cyclophanes represent an important family of macrocyclic receptors that have been extensively explored.The aromatic moieties in cyclophanes not only facilitate chemical modifications to impart water solubility but also enable forming hydrophobic cavities for guest inclusion in aqueous environments.Pioneered by Koga et al.,who reported the first inclusion complex of cyclophanes in water and solid state,numerous water-soluble cyclophanes,including derivatives of blue box,calixarenes,resorcinarenes,pillararenes,octopusarenes,biphenarenes,coronarenes,and naphthotubes,etc.,have been synthesized and subjected to investigation of the recognition capabilities in aqueous solutions.This review provides an overview of cyclophane receptors designed to bind organic guests in water.We categorize them into two classes based on the modifications made to their hydrophobic cavities:those with“exo-functionalized hydrophobic cavities”and those with“endo-functionalized hydrophobic cavities”.We introduce their distinctive features and discuss strategies to enhance recognition affinity and selectivity.This review aims to inspire the development of novel synthetic receptors with intriguing properties and foster practical applications of cyclophanes.

Organoborane cyclophanes with flexible linkers: Dynamic coordination and photo-responsive fluorescence

Stimuli-responsive macrocycles are of importance for synthetic chemistry and smart materials. In this manuscript, we report two novel organoborane cyclophanes, which were successfully synthesized by ruthenium-catalyzed olefin metathesis. They are composed of one/two boron-doped helicene π-skeletons and flexible alkyl chain linkers, thus representing a new kind of non-conjugated organoborane macrocycles. Their cyclic structures and photophysical properties, as well as Lewis acidity were theoretically and experimentally investigated. Notably, two enantiomers in one single crystal are observed for one organoborane cyclophane, owning to the presence of helical π-framework in its cyclic structure. Moreover, their Lewis acid-base adducts may dissociate in the excited state and thus display intriguing photo-responsive fluorescence properties, which can be further modulated by temperature. This study thus provides a novel design strategy for non-conjugated organoborane macrocycles, which may promote the development of stimuli-responsive macrocyclic materials with fascinating properties.

The synthesis,characterization and X-ray diffractometry structure of fluorine-containing cyclobis(paraquat-p-phenylene) tetracation

Two novel fluorine-containing cyclophanes 1 and 2 incorporating a 1,4-bismethylfluorophenylene subunits have been synthesized via the template-directed clipping methodology and their structure was characterized by ~1H NMR,^(13)C NMR, MALDI-TOF-MS and elemental analysis.X-ray diffraction analysis of the solid state molecular structure showed that the complex units are linked by non-classical C-H…F hydrogen bonding.

Molecular Recognition of Pyromellitic Imide-azacyclophane to Organic Pollutant

Anion can be identified by pyromellitic imide-azacyclophane which is one of the host compounds.This article investigated the interaction between the host and organic pollution compounds.The host and other eight compounds were optimized by DFT（density functional theory） B3LYP/6-31G level and the energy of compounds was corrected using Boys-Bemardi method.On the basis of B3LYP/6-31G optimized geometries,the RDG function and sign（λ2（r））ρ（r） function values of space points were calculated,and color RDG isosurface map was drawn.3He chemical shift was calculated by the B3LYP/6-31G method.The results showed that the eight organic pollution molecules with the host one shaped stable configurations by hydrogen bonds,respectively.The stabilization energy of complexes 4 and 7 showed repulsion（steric effects） of cyclophane cage observably affecting the stability of the complexes.The location,intensity and the type of interaction in complex 1 were analyzed through color-filled RDG isosurface map.Aromaticity calculations showed that the weak interaction reduced the transverse induction ring current in the host rings,and deteriorated the aromaticity of compounds.

Synthesis of Imidazole Cyclophane as Ligand of Binuclear Metalloprotein Models

Four imidazole cyclophanes have been synthesized by the oxidation of bis-imidazoline with barium manganate followed by cyclization with 2,6-bis(bromomethyl) pyridine in the presence of NaH. All the compounds were identified by IR, (HNMR)-H-1, MS and elemental analysis.

Synthesis and Enhanced Guest-Binding Affinities of Dendrimer-Based Cyclophane Tetramer and Octamer

Dendritic cyclophane tetramer and octamer were prepared by aminolysis of succinimidyl ester derivative of tetraaza [6.1.6.1] paracyclophane with the corresponding poly(amidoamine) dendrimers as a scaffold, followed by removal of the protecting groups. The present cyclophane tetramer and octamer showed enhanced guest-binding affinities toward fluorescent guests such as 6-p-toluidinonaphthalene-2-sulfonate and 6-anilinonaphthalene-2-sulfonate, in comparison with those of monocyclic cyclophane, reflecting multivalency effects in macrocycles.

Synthesis of a Rhodamine-Appended Cyclophane as a Fluorescence Host in Water

A cationic water-soluble cyclophane (1a) having a rhodamine moiety as a red-fluorescence fluorophore was prepared by reaction of a monoamine derivative of tetraaza[6.1.6.1]paracyclophane having three N-t-butoxycarbonyl-β-alanine residues with rhodamine B isothiocyanate, followed by removal of the protecting groups. The guest-binding behavior of 1a toward anionic guests such as dabsyl derivative and 4-(1-pyrene)butanoate was investigated by fluorescence spectroscopy. The results suggested the formation of host-guest complexes with a stoichiometric ratio of 1:1 and the binding constants (K) of the host-guest complexes were evaluated.

Synthesis of Branch-Type Cyclophane Tetramers Having a Multivalently Enhanced Guest-Binding Ability

A cationic branch-type cyclophane tetramer (1a) was synthesized by introducing three Boc-protected cyclophane derivatives into a N-acetylated tetraaza[6.1.6.1]paracy-clophane derivative as a core skeleton through DCC condensation, followed by removal of the external Boc-protecting groups. Cationic cyclophane tetramer 1a exhibited a high affinity toward an anionic and hydrophobic fluorescent guest, TNS, with binding constant of 4.8 × 105 M-1. This value of 1a was about 80-fold larger than that of the corresponding monomeric cyclophane for the identical guest, reflecting multivalent effect on the guest binding. As for electrostatic recognition, the obtained binding constant of 1a was one order of magnitude larger than that of an analogous anionic cyclophane tetramer (1b) for the identical guest. These enhanced guest-binding abilities of 1a were easily evaluated by fluorescence titration experiments.

Substrate specificity and reaction directionality of a three-residue cyclophane forming enzyme Pau B

Three-residue cyclophane-forming enzymes(3-Cy FEs) are a group of radical S-adenosylmethionine(SAM)enzymes involved in the biosynthesis of ribosomally synthesized and posttranslationally modified peptides(Ri PPs). 3-Cy FE catalyzes the crosslinking between an aromatic residue(Ω1) and a non-aromatic residue(X3) in a Ω1-X2-X3 motif to produce a cyclophane ring, a key step in the biosynthesis of the Ri PP natural product triceptide. In this study, we perform a genome-wide search for the Xye-type triceptides, showing these Ri PPs are likely class-specific and only present in gamma-proteobacteria. The 3-Cy FE Pau B from Photorhabdus australis exhibits a relaxed substrate specificity on the X3 position, but glycine in this position is not suitable for cyclophane formation. We also reconstituted the activity of Pau B in vitro,showing it produces the N-terminal cyclophane firstly, and then the C-terminal ring, whereas the middle cyclophane is produced in the last step.

Template-directed synthesis of pyridazine-containing tetracationic cyclophane for construction of[2]rotaxane

Benefiting from its bent molecular structure,3,6-pyridazinyl contained tetracationic cyclophane（1） is synthesized by template-directed method with high isolated yield up to 92%.This template-directed strategy is further utilized to efficiently construct [2]rotaxane.