Structurally isomeric two pyridino macrocycles: complexation and structures

Pyridine-based, structurally isomeric two macrocyclic compounds displayed a remarkably different complexation nature. The cage-type compound has an ideal structure for spherical cations, especially for the NH₄⁺ ion, but the reaction with some transition metals and Ln³⁺ produced its protonated species. On the other hand, its isomer formed complexes with alkali metals and lanthanides (1:1) and also with transition metals. Some structures of the complexes were clarified by crystallographic analyses.     

Synthesis and characterization of cationic iodonium macrocycles

A synthetic strategy for the high-yield preparation of iodonium containing macrocycles such as rhomboids, a square, and a pentagon is described, with the long-term objective of preparing iodonium compounds for potential molecular electronics applications. Two cationic rhomboid shaped molecules were prepared for the first time (55-70%) by the treatment of compounds 11 and 12a or 12b with Me3SiOTf. The reaction of dication 8 with 6 in the presence of Me3SiOTf gave an iodonium containing molecular square in 70% yield. In addition, a pentagon-shaped macromolecule was prepared in 60% yield. These iodonium-containing charged macromolecules were characterized by multinuclear NMR, mass spectrometry, and physical means.     

Synthesis of two isomeric dimethylthiazolophenothiazines

Two condensed four-ringed heterocyclic bases—2, 10-dimethylthiazolo[4, 5-b]phenothiazine and 2, 6-dimethylthiazolo[4, 5-c]pheno-thiazine-have been synthesized. The structure of the new heterocycles has been confirmed by their IR and UV spectra.     

两种四乙酸四氮杂环烷化合物的合成

在氢氧化钾存在下，1，4，7，10-四氮杂环十二烷与溴乙酸进行N-羧甲基化反应，得到N，N′N″N-四乙酸1，4，7，10-四氛杂环十二烷（DOTA，I），经重结晶纯化，产率88．1％．在碳酸钾存在下，1，4，8，11-四氮杂环十四烷与溴乙酸卡酯进行反应，生成N－乙酸苄酯中间体．该中间体在室温和4．04×105Pa氢气压力下，用Pd／C地催化氢解脱苄基得到N，N′N″N-四乙酸1，4，8，11－四氮杂环十四烷（TETA，Ⅲ），产率56．0％。     

Synthesis and characterization of two isomeric liquid crystal series with reactive double bonds

Two series of potentially cross-linkable liquid crystal materials derived from p-phenylenebisacrylic (series I, n(P.FB.P), n = 2-10) and p-hydroxycinnamic acid (series II, n(HC.T.HC), n = 2-10) have been synthesized and their thermal and mesomorphic properties studied. All these compounds show enantiotropic mesomorphism over a wide range of temperatures. Compounds with short terminal chains are nematic and when the terminal chain length is increased they show smectic polymorphism-smectic A and C. Most of the compounds are thermally stable over their mesophase ranges.     

Synthesis and characterization of isomeric diphenylphosphatoisosorbide acrylates

Abstract

Isosorbide is a diether diol readily available from starch, an abundant, renewable biomaterial. Because of its structure and functionality, it may serve as a base for the development of nontoxic polymer additives, particularly flame retardants. Conversion of one of the hydroxyl groups to a diphenylphosphato moiety followed by conversion of the other to an acrylate affords isomeric vinyl monomers suitable for copolymerization with a variety of monomers to generate flame-retardant polymers.     

Synthesis and structural characterization of carborane-containing neutral, self-assembled Pt-metallacycles

[structure: see text] We have combined carborane chemistry with the newly developed directional bonding strategy to synthesize neutral macrocycles. The m- and p-carborane dicarboxylates were utilized as the donor linkers in conjunction with 1,8-bis[trans-Pt(PEt3)2NO3]anthracene 3, 2,9-bis[trans-Pt(PEt3)2NO3]phenanthrene 5, and cis-Pt(PEt3)2(NO3)2 unit 6. Three new platinum-based macrocycles, 4, 7, and 8, were thus synthesized. 31P{1H} NMR as well as the X-ray characterization of Pt-metallacycles reveal the formation of single highly symmetrical neutral species.     

Synthesis and chiroptical properties of two new planar-chiral macrocycles

Could simple intraannular-arm macrocyclic systems exist in enantiopure stable forms? The effective synthesis of two representative compounds of such a class, their resolution into enantiomers, and experiments justifying their stability toward racemization are presented.     

Synthesis and characterization of oxygen and sulfur bridged aromatic macrocycles

The synthesis of nine 16–18–20–22 membered, oxygen and sulfur bridged aromatic macrocycles is reported, and reaction pathways to macrocycles formation are described. Molecular characterization of the nine compounds has been achieved by their mass spectra. Due to the cyclic nature of the compounds analyzed, the mass spectra are of particular interest. The 16–18-membered macrocycles, containing single oxygen and sulfur bridges, display very strong molecular ion intensities, while the 20–22-membered macrocycles, containing double bridges, show lower stability to electron-impact, and the molecular ion intensities are lower. Some of the salient features of the electron fragmentation processes are briefly discussed in the text.     

Synthesis, characterization, and electrochemical properties of self-assembled leaf-like CuO nanostructures

A simple hydrothermal process was used to synthesize the assembled leaf-like copper oxide (CuO) from copper hydroxide and urea in aqueous solution. The field emission scanning electron microscopy revealed that the individual CuO leaf-like nanostructure has a dimension of about 0.5–1.5 μm in length, 50–70 nm in thickness, and 80–110 nm in width, respectively. These CuO nanostructures were structurally characterized by X-ray diffraction and Raman spectroscopy, which showed that the CuO nanostructures prepared from the hydrothermal process have high crystalline properties with a monoclinic structure. X-ray photoelectron spectroscopy studies confirmed that the as-prepared sample is composed of CuO, which is consistent with X-ray diffraction patterns. The CuO nanostructures were used as electrode materials for lithium-ion batteries, demonstrating electrochemical properties of a high initial discharge capacity of approximately 1,028 mAh/g along with good cycle stability.     

Synthesis,characterization, and reactivity of self-assembled tetranuclear arene ruthenium metalla-rectangles

Self-assembly of 4,4′-bipyridine (bpy) with arene-ruthenium building blocks and 2,2′-bisbenzimidazole (H₂BiBzIm) in the presence of AgOTf (OTf = OSO₂CF₃) afforded tetranuclear cations of the type [Ru₄(η⁶-arene)₄(bpy)₂(BiBzIm)₂]⁴⁺ (arene = p-ⁱPrC₆H₄Me 1, C₆Me₆ 2), while similar reactions by use of [(η⁶-C₆Me₆)Ru(μ-Cl)Cl]₂ and excess AgOTf led to isolation of a cationic coordination network {[Ru₄(η⁶-C₆Me₆)₄(bpy)₂(BiBzIm)₂·Ag₂(OTf)₄]²⁺}_n (3), which could also be obtained by treatment of [2][OTf]₄ with AgOTf in methanol. Complex 3 is constructed by π coordination of BiBzIm(η²-carcon) with Ag(I). The coordination geometry around the silver(I) ion is pseudo-tetrahedral (taking the C=C group as one ligand). Self-assembly of only two components: [(η⁶-C₆Me₆)Ru(μ-Cl)Cl]₂ reacted with the 3-pyridyl-bian (mPy-bian) linker in the presence of limited AgOTf to give a chloro-bridged metalla-rectangle [Ru₄(η⁶-C₆Me₆)₄(μ-Cl)₄(mPy-bian)₂Ag]⁵⁺ (4), which enclosed a silver in the center. The coordination geometry around silver(I) in 4 is unusual square planar. The molecular structures of 1–4 were confirmed by X-ray crystallography along with other spectroscopic properties.     

Convergent synthesis of isomeric pairs of metallocene-containing polyether macrocycles

A general method for rapid construction of metallocene-based hosts is described. Treatment of polyether bridged bis(diphenylacetylenes) with a source of cyclopentadienyl cobalt at high temperature leads, via macrocyclization and capture of the intermediate cyclobutadiene, to macrocyclic systems tethered to an integral metallocene platform. Equal yields of the two possible structural isomers, the products of parallel or antiparallel cycloaddition of the precursor, are obtained. A combination of X-ray crystallography and NMR is employed to assign structures to the individual isomers and to assess the strength of lithium ion binding by the individual macrocycles.     

Synthesis of macrocycles containing two pyridine and two polyamine moieties via Pd-catalyzed amination

The synthesis of macrocycles containing two pyridine and two polyamine fragments was carried out by the Pd-catalyzed amination of 2,6-dihalopyridines using polyamines and dioxadiamine. Two alternative approaches were elaborated and compared: via intermediate formation of N^α,N^ω-bis(6-halopyridin-2-yl)polyamines or via 2,6-bis(polyamino)substituted pyridines. The yields of linear and cyclic products were shown to be strongly dependent on the nature of the starting polyamines and that of the halogen atom.     

Synthesis, structural characterization and anion binding studies of palladium macrocycles with hydrogen-bonding ligands

The reactions between [Pd(P-P)(OTf)2] (where P-P=dppp or dppf) and two different bipyridyl ligands (=1,3-bis(4-pyridylmethyl)urea and=1,3- bis(pyridinylmethyl)benzenedicarboxamide) containing hydrogen-bonding units have been studied. The X-ray crystal structures of three of these assemblies have been solved showing them to be the [2+2] metallo-macrocycles [Pd(P-P)(n)]2(OTf)4 [P-P=dppp, n=1, (); P-P=dppp, n=2, (); P-P=dppf, n=1, ()]. To confirm whether the dimeric assembly of one of these species () is retained in solution, several investigations have been carried out. 1H NMR studies in DMSO and high resolution ESI mass spectrometry have shown that is in equilibrium with a larger [3+3] metallo-macrocycle. The equilibrium between these two species can be modified by changing the temperature, concentration or solvent. Also, addition of certain anions (e.g. [H2PO4]-) to the mixture shifts the equilibrium favoring the formation of the [2+2] metallo-macrocycle over the [3+3] (initially present in a larger proportion).     

Synthesis and characterization of isomeric cis- and trans-pyrrone model compounds

Isomeric cis- and trans-imidazopyrrolones, obtained from the reaction of pyromellitic di-anhydride and o-phenylenediamine, were prepared as models for pyrrone polymers. The characterization of these model compounds, which represent the repeat unit of the completely cyclized polymer, provided information which could not be obtained by studying the polymer itself. Isomerism was proven by the nuclear magnetic resonance spectra of soluble ester-benzimidazole derivatives. This study indicated that a single band around 1755 cm^?1 should appear in the infrared spectrum of the completely cyclized polymer. The high melting points of the model imidazopyrrolones indicate the extreme thermal stability to be anticipated from perfectly formed pyrrone polymers.     

Synthesis, characterization and crystal structure of a novel 3D network triorganotin(IV) polymer containing two types of macrocycles

A novel triorganotin(IV) complex 1 has been synthesized and structurally characterized by elemental analysis, FT-IR, NMR (¹H, ¹¹⁹Sn) spectra and X-ray crystallography. This complex displays a 3D network structure, which contains two types of chair form macrocycles.     

Synthesis, structure and electrochemistry of ferrocene-peptide macrocycles

Redox active cyclopeptides Fc[CSA]2 (5), Fc[Gly-CSA]2 (6), Fc[Ala-CSA]2 (7), Fc[Val-CSA](2) and Fc[Leu-CSA]2 (9) (CSA = cysteamine) which are formed by the reaction of ferrocenedicarboxylic acid with peptide cystamines at high dilutions. These systems exhibit H-bonding involving the amide NH in solution as shown by their temperature dependent NMR spectra. With the exception of 5, the ferrocene macrocycles display intramolecular N...O cross-ring H-bonding in the solid state involving the amino acids proximal to the ferrocene.     

Synthesis, optical characterization, and electrochemical properties of isomeric tetraphenylbenzodifurans containing electron acceptor groups

Isomeric tetraphenylbenzodifuran systems, benzo[1,2-b:5,4]difuran and benzo[1,2-b:4,5]difuran, containing electron acceptor groups (CF(3), CN, and NO(2)) have been synthesized and studied. Their electronic absorption, fluorescence, two-photon absorption cross sections, and electrochemical properties were investigated. The absorption and emission maxima are red-shifted for the linear-conjugated systems in comparison with the corresponding isomer. Dual fluorescence was observed and the existence of a twisted intramolecular charge transfer state was confirmed by low-temperature emission experiments. Wide HOMO-LUMO energy gaps were obtained ranging from 2.53 to 3.28 eV. HOMO levels were found in the energy range of -6.03 to -6.63 eV while LUMO are within -2.55 to -3.52 eV.     

Synthesis, characterization, and luminescence properties of a new series of Eu3+-containing macrocycles

The synthesis and structural characterization of a series of neutral Eu(3+)-containing macrocyclic complexes, Eu(4)-Eu(7), are reported. The synthetic pathway herein allows for the size and functionality of the macrocycle to be tailored in one step from a common precursor (N,N' '-bis(p-isothiocyanatobenzylcarbamoylmethyl)diethylenetriamine-N,N'N' '-triacetic acid, (3) in high yield. The macrocyclic ligands 4-7 have within their structure a bis-amide derivative of diethylenetriaminepentaacetic acid (DTPA) functioning as the europium chelate that is bridged through thiourea groups by either a butyl (4), hexyl (5), octyl (6), or m-benzyl (7) linker. The two thiourea groups were designed into the host macrocycle to serve as hydrogen-bond donors to potential guest molecules that may alter the luminescence properties of the parent macrocycle. Characterization of the luminescence of Eu(4)-Eu(7) reveals an antenna effect from the ligand, and the luminescence lifetime data reveals the presence of one coordinated water molecule in aqueous solution.