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The manner of bonding between constituent atoms or molecules invariably influences the properties of materials. Perhaps no material family is more emblematic of this than porous frameworks, wherein the namesake modes of connectivity give rise to discrete subclasses with unique collections of properties. However, established framework classes often display offsetting advantages and disadvantages for a given application. Thus, there exists no universally applicable material, and the discovery of alternative modes of framework connectivity is highly desirable. Here we show that chalcogen bonding, a subclass of σ-hole bonding, is a viable mode of connectivity in low-density porous frameworks. Crystallization studies with the triptycene tris(1,2,5-selenadiazole) molecular tecton reveal how chalcogen bonding can template high-energy lattice structures and how solvent conditions can be rationalized to obtain molecularly programmed porous chalcogen-bonded organic frameworks (ChOFs). These results provide the first evidence that σ-hole bonding can be used to advance the diversity of porous framework materials.

The title compound crystallizes with half of a mol­ecule per asymmetric unit and exhibits bond lengths and angles typical of α-diketones. A network of C—H⋯F contacts and π–π stacking inter­actions is observed within the structure., The title compound, C14H6F4O2, crystallizes with half of a mol­ecule per asymmetric unit and exhibits bond lengths and angles typical of α-diketones. A network of C—H⋯F contacts and π–π stacking inter­actions is observed within the structure.

An investigation into the crystalline to amorphous phase transitions of prepared 1,3,6-substituted pentafulvenes showed the expected reversible heated melt and cooling recrystallization in only a few examples. Systematic incorporation of bulky substituents at the 6-position of the fulvene ring led to the nonreversible thermal behavior, rendering phases that were locked into glassy, vitrified states. These molecular glasses produced physically translucent and amorphous features with glass transition temperatures in the range of 61-77 °C, comparable with high-strength plastics such as polyethylene terephthalate. Additionally, the melting point transitions and the resulting heat of fusion values were found to be directly influenced by the nature of the 6-position substituent. Single crystal X-ray crystallography showed that in some cases, fulvenes possessing fused aromatics exhibited a high degree of intermolecular π-π stacking. These results point to a class of molecular glass formers as host materials possessing tunable bulk properties for potentially new optical applications.

The title compounds were prepared from 1,3-di­phenyl­cyclo­penta­diene, pyrrolidine, and the corresponding aldehydes in an ethano­lic solution. Each compound crystallizes with one mol­ecule per asymmetric unit and exhibits the alternating short and long bond lengths typical of fulvenes. A network of C—H⋯C ring inter­actions as well as C—H⋯O inter­actions is observed, resulting in the compact packing found in each structure., The title compounds, 6-cyclo­propyl-1,3-diphenylfulvene, C21H18, [systematic name: 5-(cyclo­propyl­methyl­idene)-1,3-di­phen­yl­cyclo­penta-1,3-diene], 1, and 6-(2,3-di­meth­oxy­naphth­yl)-1,3-diphenylfulvene, C30H24O2, {systematic name: 5-[(3,4-di­meth­oxy­naphthalen-2-yl)methyl­idene]-1,3-di­phenyl­cyclo­penta-1,3-di­ene}, 2, were prepared from 1,3-di­phenyl­cyclo­penta­diene, pyrrolidine, and the corresponding aldehydes in an ethano­lic solution. Each structure crystallizes with one mol­ecule per asymmetric unit and exhibits the alternating short and long bond lengths typical of fulvenes. A network of C—H⋯C ring inter­actions as well as C—H⋯O inter­actions is observed, resulting in the compact packing found in each structure.

Tetrahedral main-group compounds are normally configurationally stable, but P-epimerization of the chiral phosphiranium cations syn- or anti-[Mes*P(Me)CH2 CHPh][OTf] (Mes*=2,4,6-(t-Bu)3 C6 H2 ) occurred under mild conditions at 60 °C in CD2 Cl2 , resulting in isomerization to give a syn-enriched equilibrium mixture. Ion exchange with excess [NBu4 ][Δ-TRISPHAT] (Δ-TRISPHAT=Δ-P(o-C6 Cl4 O2 )3 ) followed by chromatography on silica removed [NBu4 ][OTf] and gave mixtures of syn- and anti-[Mes*P(Me)CH2 CHPh][Δ-TRISPHAT]⋅x[NBu4 ][Δ-TRISPHAT]. NMR spectroscopy showed that isomerization proceeded with epimerization at P and retention at C. DFT calculations are consistent with a mechanism involving P-C cleavage to yield a hyperconjugation-stabilized carbocation, pyramidal inversion promoted by σ-interaction of the P lone pair with the neighboring β-carbocation, and ring closure with inversion of configuration at P.

Five new crystal structures of perfluoropyridine substituted in the 4-position with phenoxy, 4-bromophenoxy, naphthalen-2-yloxy, 6-bromonaphthalen-2-yloxy, and 4,4′-biphenoxy are reported, viz. 2,3,5,6-tetrafluoro-4-phenoxypyridine, C11H5F4NO (I), 4-(4-bromophenoxy)-2,3,5,6-tetrafluoropyridine, C11H4BrF4NO (II), 2,3,5,6-tetrafluoro-4-[(naphthalen-2-yl)oxy]pyridine, C15H7F4NO (III), 4-[(6-bromonaphthalen-2-yl)oxy]-2,3,5,6-tetrafluoropyridine, C15H6BrF4NO (IV), and 2,2′-bis[(perfluoropyridin-4-yl)oxy]-1,1′-biphenyl, C22H8F8N2O2 (V). The dihedral angles between the aromatic ring systems in I–IV are 78.74 (8), 56.35 (8), 74.30 (7), and 64.34 (19)°, respectively. The complete molecule of V is generated by a crystallographic twofold axis: the dihedral angle between the pyridine ring and adjacent phenyl ring is 80.89 (5)° and the equivalent angle between the biphenyl rings is 27.30 (5)°. In each crystal, the packing is driven by C—H...F interactions, along with a variety of C—F...π, C—H...π, C—Br...N, C—H...N, and C—Br...π contacts. Hirshfeld surface analysis was conducted to aid in the visualization of these various influences on the packing.

The syntheses and crystal structures of the title compounds, C14H8F4N2O2 and C14H8F4N2O3, are reported. In each crystal, the packing is driven by C—H...F intertactions, along with a variety of C—H...O, C—O...π, and C—F...π contacts. Hirshfeld surface analysis was conducted to aid in the visualization of these various influences on the packing: they showed that the largest contributions to the surface contacts arise from H...F/F...H interactions, followed by H...H and O...H/H...O.

The synthesis and structures of a series of 6-aryl-1,3-diphenyl­fuvlenes with (fulvene is 5-methyl­idene­cyclo­penta-1,3-diene) varying methyl­ation patterns on the 6-phenyl substituent are reported. A network of C—H⋯π ring inter­actions consolidates the packing in each structure., The synthesis and crystal structures of a series of 6-aryl­fuvlenes (fulvene is 5-methyl­idene­cyclo­penta-1,3-diene) with varying methyl­ation patterns on the 6-phenyl substituent are reported, namely 6-(3-methyl­phen­yl)-1,3-di­phenyl­fulvene (C25H20), 6-(4-methyl­phen­yl)-1,3-di­phenyl­fulvene (C25H20), 6-mesityl-3-di­phenyl­fulvene (C27H24) and 6-(2,3,4,5,6-penta­methyl­phen­yl)-1,3-di­phenyl­fulvene (C29H28). The bond lengths are typical of those observed in related fulvenes. A network of C—H⋯π ring inter­actions consolidates the packing in each structure.

High affinity guest have been reported for the macrocyclic host cucurbit[7]uril (CB[7]), enabling widespread applications, but preventing CB[7] materials from being returned to their guest-free state for reuse. Here we present polyhedral boron clusters (carboranes) as strongly-binding, yet easily removable, guests for CB[7]. Aided by a Pd-catalyzed coupling of an azide anion, we prepared boron-functionalized 9-amino and 9-ammonium modified ortho-carboranes that bind to CB[7] with a Ka=1010 M-1. Upon treatment with base, the ortho-carboranes readily undergo deboronation to yield anionic nido-carborane, a poor guest of CB[7], facilitating recovery of guest-free CB[7]. We showcase the utility of the modified ortho-carborane guest by recycling a CB[7]-functionalized resin. With this report, we introduce stimuli-responsive decomplexation as an additional consideration in the design of high affinity host-guest complexes.

Kinetic separation of the commercially available cis/trans-(+)-limonene oxide mixture by ring opening with primary phosphido nucleophiles LiPHR (R = ferrocenyl, Ph, Cy, t-Bu, Mes* (Mes* = 2,4,6-(t-Bu)3C6H2)), followed by treatment with aqueous NH4Cl and H2O2, gave unreacted cis-(+)-limonene oxide and diastereoenriched mixtures of the secondary phosphine oxides (SPOs) PHR(trans-(+)-Lim-OH)(O), which could be separated by chromatography and/or recrystallization. This one-pot synthesis uses a cheap chiral material and commercially available primary phosphines to control the configuration of the new P-stereogenic SPOs, which are potentially useful as ligands for metal complexes in asymmetric catalysis.

Four groups of rare-earth complexes, comprising 11 new compounds, with fluorinated O-donor ligands ([K(THF)6][Ln(OC4F9)4(THF)2] (1-Ln; Ln = Ce, Nd), [K](THF)x[Ln(OC4F9)4(THF)y] (2-Ln; Ln = Eu, Gd, Dy), [K(THF)2][Ln(pinF)2(THF)3] (3-Ln; Ln = Ce, Nd), and [K(THF)2][Ln(pinF)2(THF)2] (4-Ln; Ln = Eu, Gd, Dy, Y) have been synthesized and characterized. Single-crystal X-ray diffraction data were collected for all compounds except 2-Ln. Species 1-Ln, 3-Ln, and 4-Ln are uncommon examples of six-coordinate (Eu, Gd, Dy, and Y) and seven-coordinate (Ce and Nd) LnIII centers in all-O-donor environments. Species 1-Ln, 2-Ln, 3-Ln, and 4-Ln are all luminescent (except where Ln = Gd and Y), with the solid-state emission of 1-Ce being exceptionally blue-shifted for a Ce complex. The emission spectra of the six Nd, Eu, and Dy complexes do not show large differences based on the ligand and are generally consistent with the well-known free-ion spectra. Time-dependent density functional theory results show that 1-Ce and 3-Ce undergo allowed 5f → 4d excitations, consistent with luminescence lifetime measurements in the nanosecond range. Eu-containing 2-Eu and 4-Eu, however, were found to have luminescence lifetimes in the millisecond range, indicating phosphorescence rather than fluorescence. The performance of a pair of multireference models for prediction of the Ln = Nd, Eu, and Dy absorption spectra was assessed. It was found that spectroscopy-oriented configuration interaction as applied to a simplified model in which the free-ion lanthanide was embedded in ligand-centered Lowdin point charges performed as well (Nd) or better (Eu and Dy) than canonical NEVPT2 calculations, when the ligand orbitals were included in the treatment.

Bromination of the luminescent borane, anti-B18H22, via electrophilic substitution using AlCl3 and Br2, yields the monosubstituted derivative 4-Br-anti-B18H21 as an air-stable crystalline solid. In contrast to the unsubstituted parent compound, 4-Br-anti-B18H21 possesses dual emission upon excitation with UV light and exhibits fluorescence at 410 nm and phosphorescence at 503 nm, with Φtotal = 0.07 in oxygen-free cyclohexane. Increased oxygen content in cyclohexane solution quenches the phosphorescence signal. The fluorescent signal intensity remains unaffected by oxygen, suggesting that this molecule could be used as a ratiometric oxygen probe.

Bromination of the luminescent borane, anti-B18H22, via electrophilic substitution using AlCl3 and Br2 yields the monosubstituted derivative 4-Br-anti-B18H21 as an air-stable crystalline solid. In contrast to the unsubstituted parent compound, 4-Br-anti-B18H21 product possesses dual emission upon excitation with UV light and exhibits fluorescence at 410 nm and phosphorescence at 503 nm, with Фtotal = 0.07 in oxygen-free cyclohexane. Increased oxygen content in cyclohexane solution quenches the phosphorescence signal. The fluorescent signal intensity remains unaffected by oxygen, suggesting that this molecule could be used as a ratiometric oxygen probe.

Bromination of the luminescent borane, anti-B18H22, via electrophilic substitution using AlCl3 and Br2 yields the monosubstituted derivative 4-Br-anti-B18H21 as an air-stable crystalline solid. In contrast to the unsubstituted parent compound, 4-Br-anti-B18H21 product possesses dual emission upon excitation with UV light and exhibits fluorescence at 410 nm and phosphorescence at 503 nm, with Фtotal = 0.07 in oxygen-free cyclohexane. Increased oxygen content in cyclohexane solution quenches the phosphorescence signal. The fluorescent signal intensity remains unaffected by oxygen, suggesting that this molecule could be used as a ratiometric oxygen probe.

Biodiesel is an important alternative fuel synthesized by the trans-esterification of vegetable oils, animal fats, and recycled greases. In this experiment, students prepared biodiesel through the ...

The synthesis and structural properties of a series of chromium tricarbonyl `piano-stool' complexes bearing substituted pentafulvene ligands were studied. The complexes, tricarbonyl(1,3,6-triphenylfulvene)chromium(0) benzene hemisolvate, [Cr(C24H18)(CO)3]·0.5C6H6 (I), tricarbonyl[1,3-diphenyl-6-(3-vinylphenyl)fulvene]chromium(0), [Cr(C26H20)(CO)3] (II), and tricarbonyl[1,3-diphenyl-6-(pyren-1-yl)fulvene]chromium(0), [Cr(C34H22)(CO)3] (III), each have a distorted octahedral geometry, with the fulvene coordinated in a π–η2:π–η2:π–η2 fashion. Significant deviation of the exocyclic fulvene double bond from the cyclopentadiene plane accompanies coordination. Evidence of non-covalent π–π interactions was observed in both (I) and (III), with centroid-to-centroid distances ranging from 3.330 (8) to 3.494 (8) Å.

This data article describes a detailed synthetic strategy and experimental data for the synthesis of brominated fulvene chromophores as reactive precursors/monomers for conjugated organic materials. Metal-mediated coupling reactions of brominated fulvenes would result in conjugated small molecules or polymers that would find application as organic light emitting diodes (OLEDs) and photovoltaic (PV) applications.

Stereoselective syntheses of three new rac di–(tert–butyl)ethano bridged metallocene compounds of Yb, Eu and Sm were carried out by a unique strategy involving hydrocarbon radical anion coupling of a trisubstituted pentafulvene followed by incorporation of the metal by K+ salt metathesis reactions. Reductive coupling of 1,3–diphenyl–6–(tert-butyl) fulvene with sodium naphthalenide gave the corresponding bis(cyclopentadiene) ansa–ligand precursor rac–[(CHBut)2(Ph2C5H3)2] HL. Subsequent reaction of HL with KN(SiMe3)2 afforded the corresponding di–potassium salt complex [(CHBut)2(Ph2C5H2)2]K2(THF)3 1. Reactions of 1 with LnI2 (Ln = Yb, Eu, Sm) afforded new lanthanide ansa–metallocenes, [(CHBut)2(Ph2C5H2)]2Yb(DME) 2, [(CHBut)2(Ph2C5H2)]2Eu(DME)2 3 and [(CHBut)2(Ph2C5H2)]2Sm(DME)2 4 in good yields. The ansa–europocene 3 is the first example of a Eu2+ ion complexed by an ethano–bridged cyclopentadienyl ligand. This work underscores the usefulness of hydrocarbon radical anion coupling in the construction of sterically demanding Ph2Cp based ansa–ligand frameworks for d- and f-block metallocenes.

In the title compound, [Fe(C17H12Br)2], the FeII atom is sandwiched between the eclipsed five-membered rings, with Fe...ring centroid distances of 1.649 (3) and 1.652 (3) Å. In one of the ligands, the Br atom is disordered over two locations [site occupancies = 0.839 (2) and 0.161 (2)].

The title compound, C17H19N, is a disubstituted pentafulvene obtained from the hydroamination of 1-phenyl-3-trimethylsilylethynylcyclopentadiene and has monoclinic P21/n symmetry at 100 K. C—H...π ring interactions between neighboring molecules consolidate the packing. To the authors' knowledge, this reaction is the first reported example of a non-transition metal catalyzed hydroamination with concomitant desilylation.

The title Diels–Alder product, C52H44·2CH3CN, was obtained in trace quantity as the `endo' isomer during the synthesis of 1,3-diphenyl-6-(3,5-dimethylphenyl)fulvene. One of the two co-crystallized acetonitrile molecules is linked to the main molecule by a weak C—H...N hydrogen bond.

The title compound, C15H14Br2, obtained through the reduction of 4,4′-dibromochalcone, has monoclinic P21 symmetry at 100 K. No directional interactions could be identified in the crystal.

The title iridium(III) complex crystallizes as a aceto­nitrile monosolvate and has the IrIII atom in a distorted octa­hedral coordination within a C2N2ClS coordination set., The title compound, [IrCl(C12H8NO)2{(CH3)2SO}]·H3CCN or [IrCl(fppy)2(DMSO)]·H3CCN [where fppy is 4-(pyridin-2-yl)benzaldehyde and DMSO is dimethyl sulfoxide], is a mononuclear iridium(III) complex including two fppy ligands, a sulfur-coordinating DMSO ligand, and one terminal chloride ligand that define a distorted octa­hedral coordination sphere. The complex crystallizes from 1:1 DMSO–aceto­nitrile as an aceto­nitrile solvate. In the crystal, weak C—H⋯O and C—H⋯N hydrogen-bonding inter­actions between adjacent complexes and between the aceto­nitrile solvent and the complex consolidate the packing.

Poly(phenylene vinylene) (PPV) represents an important class of conjugated, conducting polymers that have been readily exploited in the preparation of organic electronic materials. In this experiment, students prepare a PPV polymer via a facile multistep synthetic sequence with robust spectroscopic evaluation of synthetic intermediates and the final product. The synthetic sequence could be applied by university instructors as a capstone project for an undergraduate organic chemistry laboratory or as a centerpiece project for either a polymer or integrated laboratory course. The initial synthetic step could be segmented and used as a modular piece in the traditional introductory organic chemistry laboratory. In either case, the resultant PPV polymer is analyzed by UV–vis and fluorescence spectroscopy to determine the quantum yield which promotes enhanced student understanding of the photophysical properties of the material. In addition, GPC analysis is completed to reveal the molecular weight and polydispe...

The first preparation of a styryl-functionalized aryl pentafulvene 4 was carried out. In the crystal structure of 4 , the packing of fulvene molecules results in the shortest intermolecular contacts between aligned vinyl groups. Thermal reactivity studies of 4 (DSC and TGA, under N 2 ) revealed a small difference between the melting point (120 °C) and the T onset for cross-linking (125 °C), and provided strong evidence for the production of a network material ( net4 ) due to reactivity of the attached styryl group. Pyrolysis of net4 under N 2 gave a glassy carbon product in low yield as revealed by powder X-ray and TGA analyses (carbon yield (TGA) of 38% (900 °C)).

Four model bis(pentafulvene) chromophores have been prepared with a (fulvene)A–D–A(fulvene) architecture. Conjugation of the central donor group with the pendant fulvene rings was apparent from a single crystal X-ray study of the bis(pentafulvene) with 2,5-dihexyloxyphenyl as the central donor group. UV-Vis results indicated a tunable bandgap in the range of 400–700 nm by varying the nature of the central donor in this series of dyes.

A series of 1,3-diphenyl-6-alkyl/arylfulvenes was prepared, and the electrochemical properties were investigated. The addition of phenyl groups about the fulvene raised the reduction potential and helped to stabilize the electrochemically generated radical anion. The addition of various functional groups onto the phenyl ring at the 6-position of 1,3,6-triphenylfulvene results in a linear free energy relationship between reduction potential and the Hammett substituent constant, σ. Further extending the conjugation at the 6-position of 1,3-diphenyl-6-arylfulvenes increases the reversibility of the redox reactions, but does not appear to further stabilize the generated radical anion. This in-depth investigation provides evidence that the compounds studied may have utility in light-harvesting applications.

New polymers containing intact pendant-fulvene moieties have been successfully prepared from 1,3-phenyl-6-norbornenylfulvene via ring-opening metathesis polymerization (ROMP). The prepared polyfulvenes have unique electrochemical and photophysical properties which make them interesting candidates for light harvesting materials.

The novel strained compound 1,2-(1',1',2',2'-tetramethyldisilane-1',2')carborane (1) was synthesized by the reaction of 1,2-dilithiocarborane and dichlorotetramethyldisilane. Compound 1 was characterized by solution methods and its structure determined by single-crystal X-ray diffraction. In contrast to its organic analogue o-(disilanyl)phenylene, the reaction of 1 with ethanol leads to cleavage of a Si-C bond rather than a Si-Si bond. Similarly to other cyclic disilanes, exposure of a solution of 1 to oxygen leads to the insertion of an oxygen atom into the Si-Si bond. The structure of the oxygen inserted product was also determined by X-ray crystallography. The general chemistry and attempts at polymerizing 1 are briefly discussed.

Reaction of the sterically demanding ligand precursor [(CHBut)2(C5H2But2)2]K2 with SnCl2 in THF gave the air-stable ansa-stannocene complex rac[(CHBut)2(C5H2But2)2]Sn. A single-crystal X-ray structure of the ansa-stannocene revealed a C2-symmetric and slipped bent structure, with the Sn2+ displaced toward an η2 bonding mode between bridged, highly tilted, and staggered 2,4-di-tert-butylcyclopentadienyl rings.

The titanacyclopentadiene complexes [(ArO)2Ti(C4Et4)] (1a), [(ArO)2Ti(C4Et2(CH2)4)] (1b) and [(ArO)2Ti(C4But2H2)] (1c) (ArO = 2,6-diphenylphenoxide) react with allylphenylether to produce new organometallic products containing cyclohexadienemethyl and phenoxide ligands. Hydrolysis of these compounds leads to the formation of single regioisomers of substituted methylenecyclohex-3-ene along with two equivalents of 2,6-diphenylphenol and one equivalent of phenol. A reaction sequence involving initial (2+2+2) cycloaddition followed by cleavage of a phenyl ether bond is discussed.

The synthesis, structural, and electronic properties of nine 1,3-diphenyl-6-alkyl/aryl substituted pentafulvenes were studied. Pyrene ring π–π interactions were revealed from analysis of the experimental crystal packing of 1,3-diphenyl-6-(1-pyrene)fulvene and supporting DFT calculations. Photophysical properties derived from UV–vis and fluorescence emission measurements demonstrated tunable and low HOMO–LUMO band gaps for the series. The presented results point to a model synthetic approach for incorporation of extended π systems and donor-π-acceptor groups for fulvene-based electronic materials.