Core/shell oligometallic template synthesis of macrocyclic hexaoxime

A 36-membered macrocyclic hexaoxime was quantitatively obtained by [3 + 3] condensation of dialdehyde 2 with diamine 3 using La3+ (core metal) and Zn2+ (shell metal) as a novel core/shell template, while the yield was very low in the absence of the metal ions. The high yield can be attributed to the efficient formation of a 3:3:1 complex of dialdehyde 2, Zn2+, and La3+, which readily gives the macrocycle keeping the Zn3La core/shell tetranuclear cluster structure.     

Crystallization-controlled dynamic self-assembly and an on/off switch for equilibration using boronic ester formation

Macrocyclic boronic esters of different sizes can be prepared selectively from the same starting diboronic acid and 1,2-diol by means of an interesting dynamic self-assembly phenomena. More specifically, two kinds of macrocyclic boronic esters could be formed diastereoselectively and nearly quantitatively under neutral conditions by the addition of an appropriate guest molecule that acts as a template. Although a mixture of tetrol 1 and di(boronic acid) 2 in methanol gave only insoluble polymeric boronic esters, a soluble macrocyclic boronic ester, homo-[2+2], was obtained selectively in the presence of toluene as a guest molecule. Furthermore, when benzene was employed as a guest molecule, the selective formation of another macrocyclic boronic ester, hetero-[3+3], occurred. Interestingly, each of these macrocycles could be converted into the other in the presence of methanol and the appropriate guest molecule; however, under aprotic conditions, guest molecules encaged by the macrocyclic boronic ester could be exchanged without affecting its structure. Thus the presence or absence of a protic solvent could be used as a regulator to switch on or off the dynamic equilibrium of the system. In addition, investigation of the effect of reaction time, direct observation of the reaction mixture by NMR spectroscopy, and carrying out the reaction using optically active tetrol suggested that precipitation plays an essentially important role in the selective formation of the macrocyclic boronic esters. Thus, although both of [2+2] and [3+3] were present as solutes in the reaction mixture, the type of added guest molecule induced the selective precipitation of only one form of macrocyclic boronic ester, hence displacing the equilibrium of the system.     

Binuclear copper(I) macrocycles synthesized via the weak-link approach

The weak-link approach has been employed to synthesize a series of bimetallic Cu(I) macrocycles in high yield. Addition of phosphinoalkylether or -thioether ligands to [Cu(MeCN)4]PF6 produces "condensed" intermediates, [mu-(1,4-(PPh2CH2CH2X)2Y)2Cu2][PF6]2 (X = S, O; Y = C6H4, C6F4), containing strong P-Cu bonds and weaker O-Cu or S-Cu bonds. The weak bonds of these intermediates can be cleaved through ligand substitution reactions to generate macrocyclic structures, [mu-(1,4-(PPh2CH2CH2X)2Y)2(Z)nCu2][PF6]2 (X = S, O; Y = C6H4, C6F4; Z = pyridine, acetonitrile, diimines, isocyanide) in nearly quantitative yields. The incorporation of tetrahedral Cu(I) metal centers into these macrocycles provides a pathway to complexes that differ from analogous d8 square planar macrocycles generated via this approach in their increased air stability, small molecule reactivity, and ability to form multiple structural isomers. Solid-state structures, as determined by single-crystal X-ray diffraction studies, are presented for condensed intermediates and an open macrocycle     

[1+1] and [2+2] crown ethers derived from N,N-bis(2-hydroxyalkylbenzyl)alkylamine and their inclusion phenomena with metal ions

N,N-bis(2-hydroxyalkylbenzyl)alkylamine (HBA) is a derivative obtained from a single time ring opening of benzoxazines. For HBA with methyl group at ortho and para positions, and at N atom, the reaction between this derivative and ditosylated compound gives [1+1] dibenzo-monoaza-crowns. For HBA without methyl group at ortho position, the compound gives [2+2] macrocyclic ethers. The studies on inclusion phenomena using Pedersen’s and molar ratio techniques clarify the alkali metal ion guest inclusion to be 2:1 for [2+2] and 5:2 for [1+1] macrocycles.     

Synthesis and X-ray Structures of Novel Macrocycles and Macrobicycles Containing N,N-Di(pyrrolylmethyl)-N-methylamine Moiety: Preliminary Anion Binding Study

The [2 + 2] Schiff base condensation reactions between the newly synthesized dialdehyde, N,N-di(α-formylpyrrolyl-α-methyl)-N-methylamine), and ethylenediamine or p-phenylenediamine dihydrochloride readily afforded the 30- and 34-membered large size macrocycles in very high yields. Subsequent reduction reactions of these macrocycles with NaBH(4) gave the corresponding saturated macrocyclic hexaamines in good yields. The analogous reaction of the new dialdehyde with a triamine molecule afforded the [3 + 2] Schiff base macrobicycle in high yield, which was then reduced by reaction with NaBH(4) to give the saturated macrobicycle. All these compounds were characterized by spectroscopic methods. The anion binding properties of the saturated macrocycles having the ethylene and the phenylene linkers in CDCl(3) were studied by NMR titration methods. Although they have similar pyrrolic and amine NH groups their binding properties are different and interesting, owing to the conformational flexibility or rigidness rendered by the ethylene or phenylene groups, respectively. The macrocycle having the ethylene linkers binds anions in a 1:1 fashion, while the other receptor having the phenylene linkers prefers to bind anions in a sequential 1:2 fashion and has a multiple equilibria between a 1:1 and a 1:2 complexes, as shown by their binding constants, curve fittings by EQNMR, and Job plots. The X-ray structures of the 1:2 methanol, the aqua and the benzoate anion complexes of the macrocycles show two cavities in which the guests are bound, correlating with the high affinity found for the formation of stable 1:2 complexes in solution. The X-ray structure showed that the macrobicycle Schiff base adopts an eclipsed paddle-wheel shaped conformation and exhibits an out-out configuration at the bridgehead nitrogen atoms.     

Pyrrole/macrocycle/MOF supramolecular co-assembly for flexible solid state supercapacitors

Supramolecular assemblies constructed through the encapsulation of conductive polymers (CPs) by macrocyclic molecules have attracted increasing interest in the fields of supramolecular chemistry and electrochemistry. In this work, an effective strategy was reported to improve the stability and conductivity of CPs by electrochemically constructing different supramolecular assemblies composed of macrocycles and CPs. Typically, we uploaded zinc-based MOF (ZIF-8) onto carbon nanotube film (CNTF) and further electrically deposited macrocycles and CPs to gain the flexible conductive electrodes. Herein, five different supramolecular macrocycles, including α-cyclodextrin (α-CD), sulfato-β-cyclodextrin (SCD), sulfonatocalix[4]arene (SC[4]), cucurbit[6]uril (CB[6]) and cucurbit[7]uril (CB[7]) were utilized and the electrochemical performances of the assembly electrodes increased in an order of α-CD < SCD < SC[4] < CB[6] < CB[7], significantly improving the areal capacitance up to 1533 mF/cm². This strategy may provide a new way for the application of macrocyclic supramolecules in electrochemical systems.     

Microwave assisted cyclocondensation of dialdehydes with chiral diamines forming calixsalen type macrocycles

Microwave irradiation of various dialdehydes and chiral diamines afforded chiral macrocyclic imines in moderate to good yields. Linked dialdehydes predominantly form [2+2] macrocycles whereas dialdehydes without linkers yield [3+3] macrocycles. This is the first report of template-free synthesis of calixsalen-type macrocycles formed in shorter reaction times under microwave conditions. In all the reactions, the salts of chiral diamines were used in contrast to the free diamines normally employed.     

Incorporation of a Phenanthrene Subunit into a Sapphyrin Framework: Synthesis of Expanded Aceneporphyrinoids

32‐Hetero‐5,6‐dimethoxyphenanthrisapphyrins—macrocycles that link structural features of polycylic aromatic hydrocarbons and expanded porphyrins—were obtained in a straightforward [3+1] condensation reaction of dimethoxyphenanthritripyrrane and 2,5‐bis(arylhydroxymethyl)heterocyclopentadienes. The highly folded conformation of formally 4 n π‐electron macrocycles causes them to manifest only limited macrocyclic π conjugation as explored by means of NMR spectroscopic and X‐ray structural analyses, and supported by DFT calculations. Although protonation does not change their π‐conjugation characteristics, the cleavage of ether groups at the phenanthrenylene moiety yields nonaromatic 32‐hetero‐5,6‐dioxophenanthrisapphyrins.     

含吡啶-2,6-二酰亚胺单元的大环化合物合成及性质

在硫酸催化作用下,用前体二醛1[1,3-二(2'-甲酰苯氧基)丙烷]和前体二胺2[N,N'-(2-胺基苯基)-2,6-二甲酰亚胺吡啶]合成了[1+1]席夫碱大环化合物3,进一步还原得到饱和大环4。 用¹H NMR、IR、元素分析和质谱等技术手段对大环3和4的组成进行了表征。 采用X射线衍射仪测定了大环3 和4的晶体结构。 用UV-Vis光谱仪对大环3和4与系列阴离子的作用分别进行了考察,结果表明,饱和大环4仅对F^-有明显的选择性作用,并测定了该配位反应的配位比和平衡常数,进一步考察了大环3和4对甲醇的吸附性能。     

Tunable organic particles: An efficient approach from solvent-dependent Schiff base macrocycles

The synthesis of cyclopolymers upon controlling the degree of macrocyclic polymerization, followed by the discovery of new properties has attracted increasing attention in supramolecular chemistry. Herein, a Schiff-base condensation method performed at room temperature was used to control the formation of [1 + 1] and [2 + 2] macrocycles. In pure MeOH, the isomer [1 + 1] macrocycles were synthesized and organic particles such as dendritic, rods, and solid microspheres were directly precipitated from the reaction solution. The [1 + 1] macrocycles can be efficiently converted into their corresponding [2 + 2] macrocycles accompanied by the tunable morphology of the organic particles when n-hexane was added to the MeOH solution. Further studies showed that these organic particles have potential application toward the selective removal of Cd²⁺ ions with different adsorption ability in MeOH solution.     

Efficient proton-templated synthesis of 18- to 38-membered tetraimino(amino)diphenol macrocyclic ligands: structural features and spectroscopic properties

A whole range of Robson-type tetraiminodiphenol macrocyclic ligands have been prepared as their perchlorate salts [H4L](ClO4)2 in high yield (ca. 90%) by a single-step [2 + 2] condensation reaction between 4-methyl(or tert-butyl)-2,6-diformyl(or diacyl)phenols and alpha,omega-diaminoalkanes (C2-C12) in the presence of acetic acid and NaClO4. The reduction of these 18- to 38-membered macrocyclic salts with NaBH4 have afforded corresponding tetraaminodiphenol macrocycles H2L'. The X-ray crystal structures of two of the tetraiminodiphenol macrocycles with the C2 and C4 lateral chains have been determined, and the optimized configurations for all of the macrocycles have been obtained by molecular mechanics calculations. The macrocycles have been characterized by elemental analysis and by IR, absorption, emission, and NMR spectroscopic study. The protonated tetraiminodiphenol macrocycles exhibit strong fluoroscence in methanol, acetonitrile, and nitromethane and undergo quenching when treated with triethylamine. The neutral macrocycles H2L, isolated by treating [H4L](ClO4)2 with excess of triethylamine, lack luminescence, as do the reduced tetraaminodiphenol macrocycles H2L'. The hydrolytic cleavage of [H4L](ClO4)2 has been studied.     

Selective crown ether based macrocyclization: a model case study from N,N-bis(2-hydroxyalkylbenzyl)alkylamine

A model case of selective crown ether based macrocycles, i.e., [1+1] or [2+2] macrocycles, obtained from a simple reaction of N,N-bis(2-hydroxyalkylbenzyl)alkylamine, HBA, and ditosylated compounds is proposed. For HBA with the methyl group at ortho and para positions, and at N atom, 1, the reaction between this derivative and the ditosylated compound with three, four, five, or eight atom chain length gives only a [1+1] macrocycle. For HBA with the methyl group at ortho and para positions, but a cyclohexyl group at N atom, 2, the reaction gives both [1+1] and [2+2] macrocyclic types when reacting with the ditosylated compound. The present work indicates that the structure of HBA induces selective macrocyclization to provide both [1+1] and [2+2] macrocycles.     

Synthesis of New Multibenzo Oxygen–Sulfur Donor Macrocycles Containing Lactams at Room Temperature

Some new oxygen–sulfur, multibenzo macrocyclic ligands containing amide groups have been prepared using the macrocyclization process with the reaction of 2,2′-thiobis-[4-methyl(2-aminophenoxy)phenyl ether] as a symmetrical diamine with appropriate dicarboxylicacid dichlorides in moderate yields. This macrocyclization led to the formation of di- and tetramide macrocycles. These reactions were routinely carried out at ambient temperature in CH₂Cl₂ as solvent in high dilution without template effect conditions. It is found that sulfur the atom affects the rigidity of the macrocycles and diastereotopicity of nuclei in the ring of these series of macrocyclic compounds.     

Palladium‐Templated Subcomponent Self‐Assembly of Macrocycles,Catenanes, and Rotaxanes

The reaction of 2,6‐diformylpyridine with diverse amines and Pd^II ions gave rise to a variety of metallosupramolecular species, in which the Pd^II ion is observed to template a tridentate bis(imino)pyridine ligand. These species included a mononuclear complex as well as [2+2] and [3+3] macrocycles. The addition of pyridine‐containing macrocyclic capping ligands allows for topological complexity to arise, thereby enabling the straightforward preparation of structures that include a [2]catenane, a [2]rotaxane, and a doubly threaded [3]rotaxane.     

Efficient Construction and Structure Determination of Novel Macrocycles with Calixarene Bishydrazones

A series of large macrocyclic calixarene bishydrazones were efficiently synthesized by [2+2] condensation reactions of calix[4]arene 1,3‐disubstituted aldehydes with hydrated hydrazine. The X‐ray single crystal diffraction showed that macrocycles form a distinctive calixtube‐liking shape.     

Palladium‐Templated Subcomponent Self‐Assembly of Macrocycles,Catenanes, and Rotaxanes

The reaction of 2,6‐diformylpyridine with diverse amines and Pd^II ions gave rise to a variety of metallosupramolecular species, in which the Pd^II ion is observed to template a tridentate bis(imino)pyridine ligand. These species included a mononuclear complex as well as [2+2] and [3+3] macrocycles. The addition of pyridine‐containing macrocyclic capping ligands allows for topological complexity to arise, thereby enabling the straightforward preparation of structures that include a [2]catenane, a [2]rotaxane, and a doubly threaded [3]rotaxane.     

Studies on copper(II) complexes of some polyaza macrocycles derived from 1,2-diaminoethane

Syntheses of copper(II) complexes of 20-membered and 15-membered aza macrocycles 1,3,6,8,11,13,16,18-octaaza-2,7,12,17-tetrachlorocycloeicosane (OTCE, [20]-N₈) and 1,3,6,8, 11,13-hexaazacyclopentadecane (HCPD, [15]-N₆) involving metal template condensation between 1,2-diaminoethane, trichloromethane and dichloromethane, respectively, are reported. Formulation of [Cu₄(OTCE)(H₂O)₈]Cl₈ and [Cu₃(HCPD)(H₂O)₆]Cl₆ · 2H₂O and the ligand hydrochlorides OTCE · 8HCl and HCPD · 6HCl are supported by elemental analyses, conductivity measurements, and spectral studies. For a comparative cavity size effect on the stability constant, potentiometric measurements on the copper complexes of the generated macrocycles [15]-N₆ and [20]-N₈ and the structurally related larger macrocycle 1,3,6,8,11,13,16,18,21,23-decaaza-2,2,7,7,12,12,17,17,22,22-decachlorocyclopentacosane (DDCP, [25]-N₁₀, prepared recently) have been performed in aqueous solution at 25°C (μ = 0.1 M KNO₃). Very high stability constants obtained for reaction Cu²⁺ + A ? CuA²⁺ (A = ligand, log K = 20.51 and 25.87, respectively, for OTCE and DDCP systems) are a reflection on the folding of the ligand to provide a small cavity suitable for fitting of the copper ion. Further, a high equilibrium constant value for CuA²⁺ + Cu²⁺ ? Cu₂A⁴⁺ (OTCE system, log K = 14.59) or Cu₂A⁴⁺ + Cu²⁺ ? Cu₃A⁶⁺ (DDCP system, log K = 16.69) is due to suitable fitting of two and three copper ions in the 20-membered and 25-membered ring cavity of OTCE and DDCP, respectively.     

Phosphorus Containing Tri-and Hexamacrocycles

Abstract

Multisite receptors containing more than two macrocyclic cavities. despite of the fact that their syntheses, most often, require sophisticated pathways, arc of very high interest since they may allow new insights into ion channel transfer, ion conduction.[1] We report here a method which combine simple reactions, high yields (80%), with easily prepared starting reagents[2], of two new polymacrocyclic system, a tri-(r) and an hexamacrocyck(II). They were obtained by a condensation reaction between 4-formylbenzo-15-crown-5 (3 or 6 quiv, respectively) and phosphouihydrazide (1 equiv.) or hexahydrazide (1 equiv.) in tetrahydrofuran.     

Cucurbit[n]uril analogues: synthetic and mechanistic studies

[reaction: see text] The synthesis of cucurbit[n]uril analogues (18, 19, (+/-)-20, 33, 34, 35, 36, and 37) is presented. These CB[5], CB[6], and CB[7] analogues all contain bis(phthalhydrazide) walls that are incorporated into the macrocycle. The tailor-made synthesis of these CB[n] analogues proceeds by the condensation of the appropriate bis(electrophile) (4, 7, or 9) with bis(phthalhydrazide) (17), which delivers the CB[6] and CB[7] analogues in good yield, whereas the CB[5] analogue is formed in low yield. To improve the solubility characteristics of the CB[n] analogues for recognition studies in water or organic solution, the CO2Et groups were transformed to CO2H and CO2(CH2)9CH3 groups. On the basis of the results of product resubmission experiments, we conclude that these macrocycles are kinetic products. To help rationalize the good yields obtained in the CB[6] and CB[7] analogue macrocyclization reactions, we performed mechanistic studies of model methylene bridged glycoluril dimers, which suggest an intramolecular isomerization during CB[n] analogue formation.