Reversible Nucleophilic Ring-Opening of Tetraoxapentacene Derivatives: Accessing New Materials for Thermally Activated Delayed Fluorescence.

We report the unexpected nucleophilic ring-opening reaction of electron deficient dioxins in the presence of carbazole under basic conditions. This nucleophilic ring-opening reaction is reversible under basic conditions in the absence of nucleophiles. Further, we demonstrate that this unexpected reactivity can be used to prepare novel donor-acceptor compounds that are emissive in solution and as thin films and exhibit thermally activated delayed fluorescence (TADF).

A new Section Editor for Acta Cryst. B.

Introducing the new Section Editor for Acta Cryst. B.

Guest-Shuttling in a Nanosized Metallobox.

An iridium-conjoined long and narrow metallorectangle was obtained by combining a quinoxalinophenanthrophenazine-connected Janus-di-imidazolylidene ligand and pyrazine. The size and shape of this assembly together with the fused polyaromatic nature of its panels provides it with properties that are uncommon for other metallosupramolecular assemblies. For example, this nanosized 'slit-like' metallobox is able show very large binding affinities with planar organic molecules in such a way, that the cavity is asymmetrically occupied by the guest molecule.

Controlled synthesis of polycarbonate diols and their polylactide block copolymers using amino-bis(phenolate) chromium hydroxide complexes.

A diamine-bis(phenolate) chromium(III) complex, CrOH[L] ([L] = dimethylaminoethylamino-,-bis(2-methylene-4,6--butylphenolate)), 2, in the presence of tetrabutylammonium hydroxide effectively copolymerizes CO and cyclohexene oxide (CHO) into a polycarbonate diol. The resultant low molar mass (6.3 kg mol) diol is used to initiate ring-opening polymerization of -lactide with 1,8-diazabicyclo[5.

Synthesis, crystal structure, and Hirshfeld surface analysis of 3-ferrocenyl-1-(pyridin-2-yl)-1-pyrazol-5-amine.

A key step towards utilizing polynuclear metal-based systems in magnetic device applications involves the careful design of ligands. This strategic planning aims to produce metal assemblies that exhibit some kind of 'switch' mechanism. Towards this end, a ligand that incorporates a redox-active functional group (ferrocene) is reported.

Synthesis of -[1](1,6)Naphthaleno[1](1,6)naphthalenophane by Double Contractive Annulation of [2.2]Paracyclophane.

Two-directional contractive annulation of [2.2]paracyclophane has led to the synthesis of -[1](1,6)naphthaleno[1](1,6)naphthalenophane (). This [1.

Approaching the isotropic spin-ladder regime: structure and magnetism of all-pyrazine-bridged copper(II)-based antiferromagnetic ladders.

The crystal structure and magnetic properties of two all-pyrazine-bridged antiferromagnetic spin ladders are reported. The complexes, -(bis(3-X-4-pyridone)(μ-pyrazine)copper(II)(-μ-pyrazine)diperchlorate ([Cu(pz)(L)](ClO) where L = 3-X-4-pyridone and X = Br (1) or Cl (2)), contain copper(II)-based ladders in which both the rung and rail bridges are pyrazine molecules bonded through the - orbital of the copper(II) ions. This structural scaffold is proposed to approach the isotropic spin-ladder regime.

"Shadow" Synthesis, Structure, and Electronic Properties of [2.2](1,6)(1,8)Pyrenophane-1-monoene.

An unexpected side product of a McMurry reaction was found to be a new [2.2]pyrenophane consisting of two pyrene units with different substitution patterns as well as different types and degrees of distortion from planarity. The new pyrenophane exhibits both monomer and intramolecular excimer fluorescence.

The Milstein Bipyridyl PNN Pincer Complex of Ruthenium Becomes a Noyori-Type Catalyst under Reducing Conditions.

Hydrogenation of the dearomatized PNN ligand of the Milstein bipyridyl complex RuH(CO)[PNN] () gives a square-pyramidal Ru(II) product RuH(CO)[pPNN] (). The central ring of the pPNN ligand is a piperidine. A minor byproduct of the hydrogenation reaction is complex which has a dimeric structure made of two Ru(II) fragments each possessing a partly hydrogenated PNN ligand.

Pyrazine-bridged Cu(ii) chains: diaquabis(n-methyl-2-pyridone)copper(ii) perchlorate complexes.

A family of pyrazine-bridged, linear chain complexes of Cu(ii) of the formula [CuL(HO)(pz)](ClO) [pz = pyrazine; L = n-methyl-2(1H)-pyridone, n = 3 (1), 5 (2), and 6 (3)] has been prepared. Single-crystal X-ray diffraction shows six-coordinate, pyrazine-bridged chains with trans-pairs of ancillary ligands. The substituted pyridine molecules exist in their pyridone tautomers and are coordinated through the carbonyl oxygen atom.

Gram-Scale Synthesis of the 1,1,n,n-Tetramethyl[n](2,11)teropyrenophanes.

A gram-scale synthesis of a series of 1,1,n,n-tetramethyl[n](2,11)teropyrenophanes (n=7-9) has been accomplished as well as the first synthesis of the next higher homologue 1,1,10,10-tetramethyl[10](2,11)teropyrenophane. The scale-up of the original small-scale synthesis required the development of several heavily modified synthetic methods, including a chlorination/Friedel-Crafts alkylation protocol and an iodination/Wurtz coupling protocol, which were performed on 25-30 g and 30-60 g scales, respectively. Two separate sets of conditions for the key teropyrene-forming cyclodehydrogenation reaction at the end of the synthetic pathway were developed, an acid-promoted one for the two less strained congeners and an acid-free method for the two more strained homologues.

Lithium, sodium, potassium and calcium amine-bis(phenolate) complexes in the ring-opening polymerization of rac-lactide.

Compounds of Li, Na, K and Ca of a tetradentate amino-bis(phenolato) ligand were prepared. Bimetallic compounds formulated as M[L](THF) (where M = Na, n = 1 (1·THF) or Li, n = 1 (2·THF)) were synthesized via the reaction of H[L] (where [L] = 2-pyridylmethylamino-N,N-bis(2-methylene-4-methoxy-6-tert-butylphenolato) with sodium hydride or n-butyllithium, respectively, in THF. Monometallic complexes MH[L](THF) (where M = Na, n = 1 (3·THF), Li, n = 0 (4) and K, n = 0 (5)) were obtained by reaction of H[L] with MN(SiMe) where M = Na, Li, or K.

Structures, Phase Behavior, and Fluorescent Properties of 3-Phenyl-1-(pyridin-2-yl)-1-pyrazol-5-amine and Its ZnCl Complex.

The synthesis of the asymmetric ligand 3-phenyl-1-(pyridin-2-yl)-1-pyrazol-5-amine () and its single-crystal X-ray structure are reported. displays crystallographic symmetry (orthorhombic, ) higher than its molecular symmetry (point group ) and also displays supercooling, with a difference in the melting and solidification points of over 100 °C. Upon complexation with ZnCl, engages in both primary cation and secondary anion coordination via hydrogen bonding, and the complex exhibits a room-to-low-temperature single crystal-to-crystal phase transition.

Synthesis of Emissive Heteroacene Derivatives via Nucleophilic Aromatic Substitution.

A synthetic approach for preparing a variety of heterocyclic tetrahydropentacene derivatives via nucleophilic aromatic substitution reactions of bidentate nucleophiles and tetrafluoroterephthalonitrile was developed. X-ray crystallography of several products revealed that the compounds containing oxygen and nitrogen heteroatoms are highly planar and engage in π-stacking, while the compounds containing sulfur are bent and do not stack as effectively. The compounds were also highly emissive, and the heteroatom had a significant impact on the emission and electrochemical properties.

Bimetallic and trimetallic zinc amino-bis(phenolate) complexes for ring-opening polymerization of rac-lactide.

The synthesis and structural characterization of bimetallic and trimetallic zinc complexes of amino-bis(phenolate) ligands are described. Bimetallic complexes (ZnEt)2[L1] (1a), its THF adduct (ZnEt)2[L1]·THF (1a·THF), and (ZnEt)2[L2] (1b) (where [L1] = n-propylamine-N,N-bis(2-methylene-4,6-di-t-butylphenolate) and [L2] = n-propylamine-N,N-bis(2-methylene-6-t-butyl-4-methylphenolate) were prepared via reaction of the proligands H2[L1] and H2[L2] with ZnEt2. The addition of isopropanol to complex 1a to replace the ethyl groups with more nucleophilic alkoxyl groups afforded trimetallic zinc complex Zn3(i-PrO)2[L1]2 (3).

Contractive Annulation: A Strategy for the Synthesis of Small, Strained Cyclophanes and Its Application in the Synthesis of [2](6,1)Naphthaleno[1]paracyclophane.

A new synthetic strategy (contractive annulation) for the synthesis of highly strained cyclophanes has been conceived and its viability has been demonstrated through a nine-step synthesis of [2](6,1)naphthaleno[1]paracyclophane from [2.2]paracyclophane.

Morpholine-Stabilized Cationic Aluminum Complexes and Their Reactivity in Ring-Opening Polymerization of ε-Caprolactone.

The first structures exhibiting bidentate (N, O) chelation of a morpholine group to a p-block element (aluminum) have been prepared and characterized by X-ray diffraction methods: Al[L] [WCA], where [L] = 4-(2-aminoethyl)morpholinylamino- N, N-bis(2-methylene-4,6- tert-butylphenolate) and [WCA] is a weakly coordinating anion. These compounds are easily synthesized by reacting Al[L]Cl with an equimolar amount of anhydrous Lewis acid and were characterized by elemental analyses, ESI-MS, MALDI-TOF MS, H, C{H}, and multinuclear NMR spectroscopy. DFT calculations showed that Al[L] cations containing bidentate NO coordination of the morpholine group are at least 21.

Synthesis and Characterization of Liquid-Crystalline Tetraoxapentacene Derivatives Exhibiting Aggregation-Induced Emission.

A series of new tetrakis(dialkoxyphenyl) dicyanotetraoxapentacene derivatives (1 a-c) were prepared by reaction of the appropriate terphenyl diols with tetrafluoroterephthalonitrile in good yields. Compounds 1 b and 1 c, which bear hexyloxy and decyloxy side chains, exhibited columnar hexagonal mesophases, as shown by polarized optical microscopy, variable-temperature powder X-ray diffraction, and differential scanning calorimetry. Single-crystal X-ray diffraction of methoxy-substituted 1 a revealed that the dicyanotetraoxapentacene core is highly planar, consistent with the notion that these molecules are able to stack in columnar mesophases.

Gram-Scale Synthesis and Highly Regioselective Bromination of 1,1,9,9-Tetramethyl[9](2,11)teropyrenophane.

An improved synthetic pathway to the nanobelt-like 1,1,9,9-tetramethyl[9](2,11)teropyrenophane has been developed, and enables the synthesis of gram quantities of material. Key innovations are the development of a sequential chlorination/Friedel-Crafts alkylation reaction, a sequential iodination/Wurtz coupling reaction, and a room-temperature teropyrene-forming reaction. The teropyrenophane was found to form a very stable radical cation and undergo a completely regioselective fourfold bromination reaction.

Aqua-chlorido-(2-{[6-(di-methyl-amino)-pyrimidin-4-yl]sulfan-yl}pyrimidine-4,6-di-amine)-copper(II) chloride hydrate.

A copper(II) complex of the non-symmetric bidentate ligand 2-{[6-(di-methyl-amino)-pyrimidin-4-yl]sulfan-yl}pyrimidine-4,6-di-amine (1) is reported. The single-crystal X-ray structure of aqua-[aqua/chlorido-(0.49/0.

Copper(II)- and gold(III)-mediated cyclization of a thiourea to a substituted 2-aminobenzothiazole.

Benzothiazole derivatives are a class of privileged molecules due to their biological activity and pharmaceutical applications. One route to these molecules is via intramolecular cyclization of thioureas to form substituted 2-aminobenzothiazoles, but this often requires harsh conditions or employs expensive metal catalysts. Herein, the copper(II)- and gold(III)-mediated cyclizations of thioureas to substituted 2-aminobenzothiazoles are reported.

Crystallographic education in the 21st century.

There are many methods that can be used to incorporate concepts of crystallography into the learning experiences of students, whether they are in elementary school, at university or part of the public at large. It is not always critical that those who teach crystallography have immediate access to diffraction equipment to be able to introduce the concepts of symmetry, packing or molecular structure in an age- and audience-appropriate manner. Crystallography can be used as a tool for teaching general chemistry concepts as well as general research techniques without ever having a student determine a crystal structure.

Ring-opening polymerization of rac-lactide mediated by tetrametallic lithium and sodium diamino-bis(phenolate) complexes.

Lithium and sodium compounds supported by tetradentate amino-bis(phenolato) ligands, [Li2(N2O2(BuBuPip))] (1), [Na2(N2O2(BuBuPip))] (2) (where [N2O2(BuBuPip)] = 2,2'-N,N'-homopiperazinyl-bis(2-methylene-4,6-tert-butylphenol), and [Li2(N2O2(BuMePip))] (3), [Na2(N2O2(BuMePip))] (4) (where [N2O2(BuMePip)] = 2,2'-N,N'-homopiperazinyl-bis(2-methylene-4-methyl-6-tert-butylphenol) were synthesized and characterized by NMR spectroscopy and MALDI-TOF mass spectrometry. Variable temperature NMR experiments were performed to understand solution-phase dynamics. The solid-state structures of 1 and 4 were determined by X-ray diffraction and reveal tetrametallic species.

Magnesium amino-bis(phenolato) complexes for the ring-opening polymerization of rac-lactide.

Magnesium compounds of tetradentate amino-bis(phenolato) ligands, Mg[L1] (1) and Mg[L2] (2) (where [L1] = 2-pyridyl-N,N-bis(2-methylene-4-methoxy-6-tert-butylphenolato), and [L2] = dimethylaminoethylamino-N,N-bis(2-methylene-4-methyl-6-tert-butylphenolato)) were prepared. The proligands, H2[L1] and H2[L2] were reacted with di(n-butyl)magnesium in toluene to give the desired compounds in high yields. Compounds 1 and 2 exhibit dimeric structures in solutions of non-coordinating solvents as observed by NMR spectroscopy and in the solid state as shown by the single crystal X-ray structure of 2.

Oligonuclear Fe complexes (Fe, Fe4, Fe6, Fe9) derived from tritopic pyridine bis-hydrazone ligands-structural, magnetic, and Mössbauer studies.

Tri-topic pyridine bis-hydrazone ligands produce polynuclear complexes with Fe(II) and Fe(III) salts with varying nuclearity and metal ion oxidation states. Mononuclear, tetranuclear, hexanuclear, and nonanuclear examples are discussed using structural, magnetic and Mössbauer data. In one case, although X-ray data suggest a [3 × 3] Fe9 grid (space group P42/n), careful examination of the structure, in conjunction with magnetic and Mössbauer data, indicates an unusual situation where the corner and center sites are present at unit occupancy, whereas side site occupancy is ∼0.