A perylene diimide rotaxane: synthesis, structure and electrochemically driven de-threading

The first example of a [2]-rotaxane in which a perylene diimide acts as a recognition site has been synthesised and characterised. The interlocked nature of the compound has been verified by both NMR studies and an X-ray structure determination. Electrochemical investigations confirm that the nature of the redox processes associated with the perylene diimide are modified by the complexation process and that it is possible to mono-reduce the [2]-rotaxane to give a radical anion based rotaxane. Further reduction of the compound leads to de-threading of the macrocycle from the reduced PTCDI recognition site. Our synthetic strategies confirm the potential of PTCDI-based rotaxanes as viable targets for the preparation of complex interlocked species.     

Conformational effects of bay substituents on optical, electrochemical and dynamic properties of perylene bisimides: macrocyclic derivatives as effective probes

A series of diagonally and laterally bridged regioisomeric macrocycles based on 1,6,7,12-tetraaryloxy-substituted perylene bisimides (APBIs) have been synthesized and characterized. The different orientations of the aryloxy residues, that is, horizontal or perpendicular to the perylene core, in the regioisomeric macrocycles have been elucidated by NMR spectroscopy, and the dynamic properties of the laterally bridged regioisomers have been investigated by temperature-dependent NMR measurements. The influence of the different orientations of the aryloxy substituents on the electrochemical properties of APBIs is demonstrated by cyclic voltammetry, which reveals that a perpendicular orientation of the aryloxy residues relative to the perylene core leads to a substantial decrease of the LUMO energy level of the perylene bisimide electrophore. The optical properties of the regioisomeric macrocycles have been determined by UV/Vis and fluorescence spectroscopy. It has been shown that the diagonally bridged macrocycles exhibit optical properties that differ significantly from those of an open-chain reference compound, whereas the optical properties of the laterally bridged isomers resemble those of the reference system. This demonstrates that unrestricted aryloxy substituents prefer the lateral conformation in solution. Solvent-dependent fluorescent properties have been exemplified for one diagonally bridged derivative, suggesting a photoinduced electron transfer process as fluorescence quenching mechanism for APBIs. From these investigations, guidelines toward highly fluorescent APBI dyes in polar media could be derived.     

Halogenation of Dibenzoselenophene and Dibenzo[1,2]diselenine

The syntheses of the selenium containing heterocycles dibenzoselenophene ( 1 ≡ biphenSe) and dibenzo[1,2]diselenine ( 2 ≡ biphenSe₂) were optimized. The halogenation reactions of 1 and 2 with XeF₂, SO₂Cl₂, Br₂ and I₂ were performed and the corresponding products characterized. In the case of 1 , the selenium(IV) dihalogenides, biphenSeF₂ ( 3 ), biphenSeCl₂ ( 4 ), biphenSeBr₂ ( 5 ), and the adduct biphenSe·I₂ ( 6 ), were isolated and identified. The extremely sensitive selenium(IV) difluoride 3 slowly formed significant amounts of an adduct with HF of the corresponding selenium(IV) oxide biphenSeO·HF ( 3a ) upon storage in glass vessels at low temperatures. In the case of 2 , the selenium(IV) trihalogenides, biphen(SeHal₃)₂ (Hal = F, Cl, Br), were found to be extremely labile (Hal = F) or not detectable (Hal = Cl, Br). Instead, as decomposition products, the selenium chloride species Se₂Cl₂, SeCl₄ and 1 were detected. In the case of Hal = I, the stable adduct biphenSe₂·I₂ ( 7 ) was isolated. In addition to characterization by multinuclear NMR spectroscopy, several molecular structures of biphen‐selenium substituted halogenides were determined.     

Supramolecular complexes of poly(3‐Hexylthiophene)‐block (and random)‐poly[3‐(2‐(6‐carboxyhexyl)methyl)thiophene] copolymers with perylene bisimide

Block and random copolymers of poly(3‐hexylthiophene) and poly[3‐(2‐(6‐carboxyhexyl)methyl)thiophene] with side‐chain carboxylic functionality ((P3HT‐b‐P3COOH) and (P3HT‐r‐P3COOH) were developed by Grignard Metathesis (GRIM) polymerization. The carboxylic functionality was introduced in the side chain via the oxazoline route. Both the block and random polythiophene copolymers were complexed with pyridine functionalized perylene bisimide to obtain supramolecular block and random polymer complexes. The complex formation in both systems was confirmed by ¹H NMR, WXRD and SAXS studies. An expansion of d spacing upon complex formation was observed in both the block and random copolymer, which could be traced by WXRD. Hole and electron mobilities measured for the supramolecular complexes indicated values which were higher by an order of magnitude for the supramolecular block complex (μ_h ≈ 2.9 × 10⁻⁴ cm²/Vs; μ_e ≈ 3.1 × 10⁻⁶ cm²/Vs) as compared to the random (μ_h ≈ 1.4 × 10⁻⁵ cm²/Vs; μ_e ≈ 4.7 × 10⁻⁷ cm²/Vs) copolymer. These results are indicative of the higher degree of disorder prevailing in the films of random copolymer system compared to the block copolymer. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1574–1583     

One Fluorophore-Two Sensing Films: Hydrogen-Bond Directed Formation of a Quadruple Perylene Bisimide Stack

Elaborately designed π-stacked molecular aggregates are significant for modulation of photophysical properties of polycyclic aromatic hydrocarbons (PAHs). Herein, a double hydrogen-bonds trussed di(pyridyl)pyrrole-perylene bisimide (HDPP-PBI) was designed and its dimerization behavior was studied. HDPP-PBI tends to form a quadruple PBI stack with a dimerization constant of ∼5.56×10⁶ M⁻¹. The dimerization was ascribed to synergistic intramolecular double hydrogen-bonds formation and intermolecular π-π stacking. Addition of CF₃COOH, a hydrogen bond blocker, promotes the dimer to monomer transition. Accordingly, two distinct fluorescent films were prepared by drop-casting of the dimerized or the monomeric HDPP-PBI onto a substrate surface. Interestingly, the less-emissive PBI quadruple stack-based film showed a turn on response to acetone vapor, while the highly emissive HDPP-PBI-based film exhibited fluorescence quenching upon exposure to triethylamine vapor. We believe that the discovered synergistic effect in the PBI aggregates would enlighten the design of new PAHs aggregates with defined structures.     

Synthesis and Structures of N‐Alkyl‐1,13‐dimethoxychromeno‐ [2,3,4‐kl]acridinium Salts: The Missing Azaoxa[4]helicenium

Helical structures are interesting due to their inherent chirality. Helicenium ions are triarylmethylium structures twisted into configurationally stable helicenes through the introduction of two heteroatom bridges between the three aryl substituents. Of the configurationally stable [4]helicenium ions, derivatives with sulfur, oxygen and nitrogen bridges have already been synthesised. However, one [4]helicenium ion has proven elusive, until now. We present herein the first synthesis of the 1,13‐dimethoxychromeno[2,3,4‐kl]acridinium (DMCA⁺) [4]helicenium ion. A series of six differently N‐substituted DMCA⁺ ions as their hexafluorophosphate salts are reported. Their cation stability was evaluated and it was found that DMCA⁺ is ideally suited as a phase‐transfer catalyst with a pK_R+ of 13.0. The selectivity of nucleophilic addition to the central carbon atom of DMCA⁺ has been demonstrated with diastereotopic ratios of up to 1:10. The single‐crystal structures of several of the DMCA⁺ salts were determined, and structural differences between N‐aryl‐ and N‐alkyl‐substituted cations were observed. The results of a comparative study of the photophysics of the [4]helicenium ions are presented. DMCA⁺ is found to be a potent red‐emitting dye with a fluorescence quantum yield of 20 % in apolar solvents and a fluorescence lifetime of 12 ns. [4]Helicenium ions, including DMCA⁺, all suffer from solvent‐induced quenching, which reduces the fluorescence quantum yields significantly (?_fl<5 %) in polar solvents. A difference in photophysical properties is observed between N‐aryl‐ and N‐alkyl‐substituted DMCA⁺, which has tentatively been attributed to a difference in molecular conformation.     

Expedited analysis of DFT outputs: Introducing moanalyzer

MOAnalyzer, a Matlab‐based program, has been developed to facilitate the analysis of density functional theory output files from ORCA. The program allows the user to define fragments within a molecule and then provides information on the contribution of each fragment to the molecular orbitals based on the Loewdin population analysis. Correlations to spectroscopy (X‐ray absorption and X‐ray emission) are also obtained, and the resulting information can be visualized in tables or MO diagrams. © 2012 Wiley Periodicals, Inc.     

Chlor(trifluorphosphan)gold(I): [Au(PF3)Cl]

Chloro(trifluorophosphane)gold(I): [Au(PF₃)Cl] X‐ray quality crystals of [Au(PF₃)Cl] (orthorhombic, Pnma) are obtained from a toluene / pentane solution at 6 °C. According to the result of the X‐ray structural analysis, [Au(PF₃)Cl] contains an almost linear F₃P‐Au‐Cl unit. The shortest Au‐Au contacts between two of these units are 3.3495(9) Å.     

新型非对称二苯并[b,f][1,5]二氮杂环辛四烯的合成

以两种不同取代的2-氨基二苯甲酮为原料,氯苯为溶剂,BF3-Et2O为脱水剂,通过分子间脱水一步环化缩合制备非对称二苯并[b,f][1,5]二氮杂环辛四烯衍生物。运用HPLC监控反应过程,优化合成工艺,得到最佳反应条件为:等物质的量的两种不同取代2-氨基二苯甲酮和BF3-Et2O,在氯苯中回流反应12 h。化合物4a^4c为新化合物,其结构经1H NMR,13C NMR和MS(ESI)表征。     

Preparation and Properties of Cyclopalladated Complexes of Dibenzo[a,c]phenazine and Dibenzo[f,h]quinoxaline with Ethylenediamine

Russian Journal of General Chemistry -     

二苯并[b,f][1,5]二氮杂芳辛四烯衍生物的合成及拆分

以邻氨基二苯甲酮为原料,经自身缩合环化合成了3种二苯并[1,5]二氮杂芳辛四烯衍生物(1a~1c);以邻苯二甲酸酐和溴苯为原料经傅-克反应制得中间体2-(4-溴苯甲酰溴)苯甲酸(M1);M1经叠氮化后自缩合制得6,12-二(4-溴苯基)二苯并[b,f][1,5]二氮杂环辛四烯(1d);以邻氨基苯甲酸甲酯为原料,经自身缩合环化制得中间体二苯并[b,f][1,5]二氮杂环辛四烯-6,12(5H,11H)-二酮(M2);M2经氯化合成6,12-二氯二苯并[b,f][1,5]二氮杂环辛四烯(1e),化合物1a~1e的结构经~1H NMR,~(13)C NMR和ESI-MS表征,其中化合物1c为新化合物。利用超临界色谱(SFC)技术对化合物1a~1e实现了手性拆分,获得5对具有高旋光度的光学活性异构体(ee99%)。     

Thermal Stability and Molecular Ordering of Organic Semiconductor Monolayers: Effect of an Anchor Group

The thermal stability and molecular order in monolayers of two organic semiconductors, PBI‐PA and PBI‐alkyl, based on perylene derivatives with an identical molecular structure except for an anchor group for attachment to the substrate in PBI‐PA, are reported. In situ X‐ray reflectivity measurements are used to follow the stability of these monolayers in terms of order and thickness as temperature is increased. Films have thicknesses corresponding approximately to the length of one molecule; molecules stand upright on the substrate with a defined structure. PBI‐PA monolayers have a high degree of order at room temperature and a stable film exists up to 250 °C, but decomposes rapidly above 300 °C. In contrast, stable physisorbed PBI‐alkyl monolayers only exist up to 100 °C. Above the bulk melting point at 200 °C no more order exists. The results encourage using anchor groups in monolayers for various applications as it allows enhanced stability at the interface with the substrate.     

Preparation of Nitrogen Heterocycles of Spiro[Furo[2,3‐d]‐Pyrimidine]Pyrimidine Derivatives

Abstract

The NMR evaluation of the reaction progression of the bromination of heterocyclic dibarbiturates was used to develop an efficient synthetic procedure for the preparation of heterocyclic spiro[furo]pyrimidines. The structure of one of these compounds was confirmed by X‐ray analysis.     

NaSc3[HPO3]2[HPO2(OH)]6: Synthesis,Crystal Structure,and Thermal Decomposition

NaSc₃[HPO₃]₂[HPO₂(OH)]₆ was prepared by use of a phosphorus acid flux route. The crystal structure was determined from single‐crystal X‐ray diffraction data: triclinic, space group P$\bar{1}$ (No. 2), a = 7.4507(11) Å, b = 9.6253(17) Å, c = 9.6141(16) Å, α = 115.798(4)°, β = 101.395(4)°, γ = 101.136(3)°, V = 577.29(16) Å³ and Z = 1. The crystal structure of NaSc₃[HPO₃]₂[HPO₂(OH)]₆ contains two kinds of phosphate(III) groups: HPO₃^2– and HPO₂(OH)^–. Phosphate(III)‐tetrahedra, NaO₆ and ScO₆ octahedra together form a (3,6)‐connected net. During heating hydrogen and water are released and Sc[PO₃]₃ is formed as the main crystalline decomposition product.     

Platinum complexes of dibenzo[1,2]dithiin, dibenzo[1,2]dithiin oxides and related polyaromatic hydrocarbon ligands

The synthesis of platinum bisphosphine complexes of biphenyl- 2,2'-dichalcogenates and the oxides of dibenzo[1,2]dithiin and related ligand systems by oxidative addition to [Pt(PPh(3))(4)] is reported. We also describe the synthesis of a new compound, dibenzothiophen-4-yldiselenide and its simple platinum complex (obtained by oxidative addition). All complexes have been fully characterised, principally by using multinuclear NMR spectroscopy and in six cases by means of single-crystal X-ray diffraction studies. The majority are simple S/S or Se/Se complexes, however the addition of dibenzo[1,2]dithiin trioxide to [Pt(PPh(3))(4)] gives a bimetallic system, [Pt[2-[S(O)],2'-[S(O)(2)]-biphen}(PPh(3))](2), containing a central Pt(2)S(2)O(2) core in which the ligand behaves as a tridentate S,S,O donor.     

区域选择性合成二苯并[d,f][1,3]二噁烷

针对二苯并[d,f][1,3]二噁烷传统制备方法中易产生二羟基联苯乙烯副产物的缺点,本文以路易斯酸性胍盐离子液体为催化剂,2,2'-二羟基联苯和端基炔为原料,高区域选择性的合成了二苯并[d,f][1,3]二噁烷,收率39%~84%。 本方法适用于各种端基炔。路易斯酸性胍盐离子液体循环利用5次,活性不变。     

Synthesis and Structural Characterization of the Tetrakis(methimazolyl)borates Li[Bmt4] and [Ru(p‐cymene)(Bmt4)][PF6]

The lithium tetrakis(methimazolyl)borate, Li[Bmt₄], is accessible from the reaction of Li[BH₄] with four equivalents of methimazole. The crystal structure of Li[Bmt₄] supported by four water molecules is described. Reaction of Li[Bmt₄] with [Ru(p‐cymene)Cl₂]₂ and subsequent treatment with NH₄PF₆ in CH₃CN results in the formation of the complex [Ru(p‐cymene)(Bmt₄)][PF₆]. In addition, we report the result of the X‐ray structure analysis of the chiral Ru complex [Ru(p‐cymene)(Bmt₄)][PF₆].