Synthesis of a Hemispherical Geodesic Phenine Framework by a Polygon Assembling Strategy

A synthetic strategy to construct large geodesic structures of phenine (1,3,5‐trisubstituted benzene) was devised. In this strategy, five pentagons were assembled on an omphalos pentagon, and bridging peripheral pentagons furnished five additional hexagons. Thirty phenine units were synthetically assembled to afford a large C₂₂₀H₁₈₀ molecule with a phenine framework isoreticular to a hemispherical, bisected segment of C₆₀. Although a hemispherical structure of the phenine framework was suggested by solution‐phase NMR spectra, crystallographic analysis revealed an oval‐like deformation of the molecular shape. In‐depth structural analyses, including theoretical calculations, showed that structural fluctuations observed as variations in the biaryl torsion angles allowed structural deformations and, at the same time, that the dynamic fluctuations resulted in the spectroscopic observation of a hemisphere as a time‐averaged structure.     

Curved Phenine Normal Vectors: Geometric Measures of Geodesic Phenine Frameworks

A vector was introduced to quantitatively describe the pyramidalization of 1,3,5‐trisubstituted benzene (phenine). The vector, named curved phenine normal vector (CPNV), defined the direction of pyramidalization of the trigonal phenine panel and quantified the degree of pyramidalization. The relative orientation of the two CPNVs further defined a dihedral angle, which quantified interphenine torsions. The CPNV analysis visually showed the geometric features of nanometer‐sized molecules by revealing the important role of torsions. Biased electrostatic potentials were also correlated with CPNV pyramidalizations.     

Cyclotetrabenzoin: Facile Synthesis of a Shape‐Persistent Molecular Square and Its Assembly into Hydrogen‐Bonded Nanotubes

Cyanide‐catalyzed benzoin condensation of terephthaldehyde produces a cyclic tetramer, which we propose to name cyclotetrabenzoin. Cyclotetrabenzoin is a square‐shaped macrocycle ornamented with four α‐hydroxyketone functionalities pointing away from the central cavity, the dimensions of which are 6.9×6.9 Å. In the solid state, these functional groups extensively hydrogen bond, resulting in a microporous three‐dimensional organic framework with one‐dimensional nanotube channels. This material exhibits permanent—albeit low‐porosity, with a Langmuir surface area of 52 m² g^?1. Cyclotetrabenzoin’s easy and inexpensive synthesis and purification may inspire the creation of other shape‐persistent macrocycles and porous molecular crystals by benzoin condensation.     

Synthesis and Supramolecular Assemblies of Tripodal 1,3,5‐Tris(phenoxymethyl)‐2,4,6‐triethylbenzene Analogues

Tripodal 1,3,5‐tris(phenoxymethyl)‐2,4,6‐triethylbenzene analogues have been synthesized and structurally characterized by IR, ¹H NMR and ¹³C NMR spectroscopy and HRMS, and additionally, the single crystal structures of compounds bearing ortho‐ ( 7 ), meta‐ ( 9 ) and para‐hydroxymethyl ( 11 ) functions have been determined by X‐ray diffraction analysis. The structural study revealed that compounds 7 , 9 , and 11 do not adopt the expected 1,3,5‐alternate conformation in the solid state. The packing diagrams of compounds 7 , 9 , and 11 revealed that six hydrophilic hydroxymethyl groups from six individual molecules ( 7 , 9 and 11 ) were arranged in close contact via intermolecular hydrogen‐bond interactions. For compounds 7 and 9 , the six hydroxyl groups formed a distorted hexagonal ring; however, formation of such a hexagonal ring was not clear in the case of compound 11 . Compounds 9 and 11 were found to form hydrophobic cavities via intermolecular hydrogen‐bond interactions in the solid state, and the cavities were occupied by two ethyl groups from the two cavity‐forming molecules.     

Synthesis,Structure, and Molecular Recognition of S6‐ and (SO2)6‐Corona[6](het)arenes: Control of Macrocyclic Conformation and Properties by the Oxidation State of the Bridging Heteroatoms

We report herein the synthesis, structure, and molecular recognition of S₆‐ and (SO₂)₆‐corona[6](het)arenes, and demonstrate a unique and efficient strategy of regulating macrocyclic conformation and properties by adjusting the oxidation state of the heteroatom linkages. The one‐pot nucleophilic aromatic substitution reaction of 1,4‐benzenedithiol derivatives, biphenyl‐4,4′‐dithiol and 9,9‐dipropyl‐9H‐fluorene‐2,7‐dithiol with 3,6‐dichlorotetrazine afforded S₆‐corona[3]arene[3]tetrazines. These compounds underwent inverse‐electron‐demand Diels–Alder reaction with enamines and norbornadiene to produce S₆‐corona[3]arene[3]pyridazines. Facile oxidation of sulfide linkages yielded (SO₂)₆‐corona[3]arene[3]pyridazines. All corona[6](het)arenes adopted generally hexagonal macrocyclic ring structures; however, their electronic properties and conformation could be fine‐tuned by altering the oxidation state of the sulfur linkages. Whereas (SO₂)₆‐corona[3]arene[3]pyridazines were electron‐deficient, S₆‐corona[3]arene[3]pyridazines acted as electron‐rich macrocyclic hosts that recognized various organic cations in both aqueous and organic solutions.     

一个结构新颖的含有反三棱柱结构单元的钴的多聚物的研究

采用1,4-二(1-H-苯并咪唑基)丁烷 (bbbi) 与CoSO₄•7H₂O反应得到一个结构新颖的金属—有机多聚物[Co(bbbi)_1.5(SO₄)]_n1. 在多聚物1中，中心离子Co(II)通过配体bbbi桥连在一起形成一个含有反三棱柱结构单元的二维层状结构. 每个反三棱柱结构单元由六个bbbi配体和六个Co(II)离子组成. 通过热分析我们发现，该化合物在147 ^oC以下是稳定的，若继续升温则被氧化并在787 ^oC时分解为 Co₂O₃，升温至914 ^oC时最终残余物为CoO。     

Multicomponent Self‐Assembly with a Shape‐Persistent N‐Heterotriangulene Macrocycle on Au(111)

Multicomponent network formation by using a shape‐persistent macrocycle ( MC6 ) at the interface between an organic liquid and Au(111) surface is demonstrated. MC6 serves as a versatile building block that can be coadsorbed with a variety of organic molecules based on different types of noncovalent interactions at the liquid–solid interface. Scanning tunneling microscopy (STM) reveals the formation of crystalline bicomponent networks upon codeposition of MC6 with aromatic molecules, such as fullerene (C₆₀) and coronene. Tetracyanoquinodimethane, on the other hand, was found to induce disorder into the MC6 networks by adsorbing on the rim of the macrocycle. Immobilization of MC6 itself was studied in two different noncovalently assembled host networks. MC6 assumed a rather passive role as a guest and simply occupied the host cavities in one network, whereas it induced a structural transition in the other. Finally, the central cavity of MC6 was used to capture C₆₀ in a complex three‐component system. Precise immobilization of organic molecules at discrete locations within multicomponent networks, as demonstrated here, constitutes an important step towards bottom‐up fabrication of functional surface‐based nanostructures.     

Fluorinated Musk Fragrances: The CF2 Group as a Conformational Bias Influencing the Odour of Civetone and (R)‐Muscone

The difluoromethylene (CF₂) group has a strong tendency to adopt corner over edge locations in aliphatic macrocycles. In this study, the CF₂ group has been introduced into musk relevant macrocyclic ketones. Nine civetone and five muscone analogues have been prepared by synthesis for structure and odour comparisons. X‐ray studies indeed show that the CF₂ groups influence ring structure and they give some insight into the preferred ring conformations, triggering a musk odour as determined in a professional perfumery environment. The historical conformational model of Bersuker and co‐workers for musk fragrance generally holds, and structures that become distorted from this consensus, by the particular placement of the CF₂ groups, lose their musk fragrance and become less pleasant.     

Separation of Arylenevinylene Macrocycles with a Surface‐Confined Two‐Dimensional Covalent Organic Framework

A two‐dimensional surface covalent organic framework, prepared by a surface‐confined synthesis using 4,4′‐azodianiline and benzene‐1,3,5‐tricarbaldehyde as the precursors, was used as a host network to effectively immobilize arylenevinylene macrocycles (AVMs). Thus AVMs could be separated from their linear polymer analogues, which are the common side‐products in the cyclooligomerization process. Scanning tunneling microscopy investigations revealed efficient removal of linear polymers by a simple surface binding and solvent washing process.     

Total Synthesis and Conformational Study of Callyaerin A: Anti‐Tubercular Cyclic Peptide Bearing a Rare Rigidifying (Z)‐2,3‐ Diaminoacrylamide Moiety

The first synthesis of the anti‐TB cyclic peptide callyaerin A ( 1 ), containing a rare (Z)‐2,3‐diaminoacrylamide bridging motif, is reported. Fmoc‐formylglycine‐diethylacetal was used as a masked equivalent of formylglycine in the synthesis of the linear precursor to 1 . Intramolecular cyclization between the formylglycine residue and the N‐terminal amine in the linear peptide precursor afforded the macrocyclic natural product 1 . Synthetic 1 possessed potent anti‐TB activity (MIC₁₀₀=32 μm ) while its all‐amide congener was inactive. Variable‐temperature NMR studies of both the natural product and its all‐amide analogue revealed the extraordinary rigidity imposed by this diaminoacrylamide unit on peptide conformation. The work reported herein pinpoints the intrinsic role that the (Z)‐2,3‐diaminoacrylamide moiety confers on peptide bioactivity.     

A Hydrophobic Metal–Organic Framework Based on Cubane‐Type [Co4(μ3‐F)3(μ3‐SO4)]3+ Clusters for Gas Storage and Adsorption Selectivity of Benzene over Cyclohexane

Hydrophobic metal‐organic frameworks (MOFs) not only have high water stability, but also exhibit high adsorption capacity towards organic molecules, in particular hydrocarbons. Herein we report a rare metal fluoride organic framework MFOF‐1 with high hydrophobicity, which is constructed from unprecedented fluoride‐ and sulfate‐bridged cubane‐type tetranuclear cobalt clusters. MFOF‐1 consists of three types of polyhedral cages with face‐sharing configurations, and possesses a novel (3,9)‐connected 3D+3D→3D self‐interpenetrating array or the rare pyr topology. MFOF‐1 shows high thermal stability and high stability in water and even acid/base aqueous solutions, and exhibits rather high H₂ and CO₂ storage capacities at ambient pressure. Remarkably, MFOF‐1 shows little adsorption of water but considerably high uptakes of methanol, n‐hexane, cyclohexane, and benzene, and exhibits a certain degree of adsorption selectivity of benzene over cyclohexane.     

Potassium 4,4′‐Bis(dinitromethyl)‐3,3′‐azofurazanate: A Highly Energetic 3D Metal–Organic Framework as a Promising Primary Explosive

Environmentally acceptable alternatives to toxic lead‐based primary explosives are becoming increasingly important for energetic materials. In this study, potassium 4,4′‐bis(dinitromethyl)‐3,3′‐azofurazanate, comprising two dinitromethyl groups and an azofurazan moiety, was synthesized and isolated as a new energetic 3D metal–organic framework (MOF). Several attractive properties, including a density of 2.039 g cm^?3, a decomposition temperature of 229 °C, a detonation velocity of 8138 m s^?1, a detonation pressure of 30.1 GPa, an impact sensitivity of 2 J, and friction sensitivity of 20 N make 4 a good candidate as a green primary explosive.     

Macrocycles All Aflutter: Substitution at an Allylic Center Reveals the Conformational Dynamics of [13]‐Macrodilactones

The shapes adopted by large‐ring macrocyclic compounds play a role in their reactivity and their ability to be bound by biomolecules. We investigated the synthesis, conformational analysis, and properties of a specific family of [13]‐macrodilactones as models of natural‐product macrocycles. The features of our macrodilactones enabled us to study the relationship between stereogenic centers and planar chirality through the modular synthesis of new members of this family of macrocycles. Here we report on insights gained from a new [13]‐macrodilactone that is substituted at a position adjacent to the alkene in the molecule. Analysis of the compound, in comparison to an α‐substituted regioisomer, by using X‐ray crystallography, NMR coupling constants, and reaction‐product characterization in concert with computational chemistry, revealed that the alkene unit is dynamic. That is, the data support a model in which the alkene in our [13]‐macrodilactones oscillates between two conformations. A difference in reactivity of one conformation compared to the other leads to manifestation of this dynamic behavior. The results underscore the local conformational dynamics observed in some natural‐product macrocycles, which could have implications for biomolecule binding.     

Effects of Fluorine Substitution on the Shape of Neurotransmitters: the Rotational Spectrum of 2‐(2‐Fluorophenyl)Ethanamine

The effects of fluorination on the conformational landscape of adrenergic neurotransmitters is exemplified trough the conformation analysis of 2‐(2‐F‐phenyl)ethanamine (2FPEA) carried out by microwave spectroscopy and quantum chemical calculations. Five different conformers of the nine possible stable ones for 2FPEA are observed by molecular‐beam Fourier‐transform microwave spectroscopy. Their unambiguous identification is possible by comparing the experimental rotational constants and the quadrupole coupling constants with those obtained by quantum chemical calculations carried out at the MP2/6‐311++G(d,p) level of theory. The relative abundances of the conformers in the jet are estimated from the relative intensities in the observed spectra. A qualitative agreement between experimental and theoretical energies was found, and the remaining deviations are explained by population transfer taking place during the adiabatic expansion. The energy landscape, which also takes the interconversion barriers between the conformers into consideration, is thus characterized completely by the strong interplay of quantum chemical methods and precise experimental data. Significant changes in energy and structure of the 2FPEA conformers are found compared to those obtained for the prototype molecule 2‐phenylethanamine (PEA).     

A one‐dimensional manganese(III)–porphyrin coordination polymer: crystal structure and photophysical properties

A novel manganese(III)–porphyrin complex, namely, catena‐poly[[chloridomanganese(III)]‐μ₂‐5,10,15,20‐tetrakis(pyridin‐3‐yl)‐21H,23H‐porphinato(2?)‐κ⁵N²¹,N²²,N²³,N²⁴:N⁵], [MnCl(C₄₀H₂₄N₈)]_n, 1 , was prepared by the hydrothermal reaction of manganese chloride with 5,10,15,20‐tetrakis(pyridin‐3‐yl)‐21H,23H‐porphine. The crystal structure was determined by single‐crystal X‐ray diffraction. The porphyrin macrocycle exhibits a saddle‐like distortion geometry. The Mn^III atom has a six‐coordination geometry. Each porphyrin unit links to two neighbouring units to yield a one‐dimensional coordination polymer. These chains are further interlinked by hydrogen bonds to form a two‐dimensional network. The complex shows red photoluminescence emission bands in ethanol solution, which can be attributed to ligand‐to‐ligand charge transfer (LLCT) accompanied by partial metal‐to‐ligand charge transfer (MLCT), as revealed by TDDFT calculations.     

Metallomacrocycles with a Difference: Macrocyclic Complexes with Exocyclic Ruthenium(II)‐Containing Domains

The templated synthesis of organic macrocycles containing rings of up to 96 atoms and three 2,2′‐bipyridine (bpy) units is described. Starting with the bpy‐centred ligands 5,5′‐bis[3‐(1,4‐dioxahept‐6‐enylphenyl)]‐2,2′‐bipyridine and 5,5′‐bis[3‐(1,4,7‐trioxadec‐9‐enylphenyl)]‐2,2′‐bipyridine, we have applied Grubbs’ methodology to couple the terminal alkene units of the coordinated ligands in [FeL₃]²⁺ complexes. Hydrogenation and demetallation of the iron(II)‐containing macrocyclic complexes results in the isolation of large organic macrocycles. The latter bind {Ru(bpy)₂} units to give macrocyclic complexes with exocyclic ruthenium(II)‐containing domains. The complex [Ru(bpy)₂(L)]²⁺ (isolated as the hexafluorophosphate salt), in which L=5,5′‐bis[3‐(1,4,7,10‐tetraoxatridec‐12‐enylphenyl)]‐2,2′‐bipyridine, undergoes intramolecular ring‐closing metathesis to yield a macrocycle which retains the exocyclic {Ru(bpy)₂} unit. The poly(ethyleneoxy) domains in the latter macrocycle readily scavenge sodium ions, as proven by single‐crystal X‐ray diffraction and atomic absorption spectroscopy data for the bulk sample. In addition to the new compounds, a series of model complexes have been fully characterized, and representative single‐crystal X‐ray structural data are presented for iron(II) and ruthenium(II) acyclic and macrocyclic species.