White Light Emission and Second Harmonic Generation from Secondary Group Participation (SGP) in a Coordination Network

We describe a white emitting coordination network solid that can be conveniently applied as a thin film onto a commercial UV-LED lamp for practical white lighting applications. The solid state material was discovered in an exercise of exploring molecular building blocks equipped with secondary groups for fine-tuning the structures and properties of coordination nets. Specifically, CH₃SCH₂CH₂S- and (<i>S</i>)-CH₃(OH)­CHCH₂S- (2-hydroxylpropyl) were each attached as secondary groups to the 2,5- positions of 1,4-benzenedicarboxylic acid (bdc), and the resultant molecules (<b>L1</b> and <b>L2</b>, respectively) were crystallized with Pb­(II) into the topologically similar 3D nets of Pb<b>L1</b> and Pb<b>L2</b>, both consisting of interlinked Pb-carboxyl chains. While the CH₃S- groups in Pb<b>L1</b> are not bonded to the Pb­(II) centers, the hydroxy groups in Pb<b>L2</b> participate in coordinating to Pb­(II) and thus modify the bonding features around the Pb­(II), but only to a slight and subtle degree (e.g., Pb–O distances 2.941–3.116 Å). Interestingly, the subtle change in structure significantly impacts the properties, i.e., while the photoluminescence of Pb<b>L1</b> is yellowish green, Pb<b>L2</b> features bright white emission. Also, the homochiral side group in Pb<b>L2</b> imparts significant second harmonic generation, in spite of its seemingly weak association with the main framework (the NLO-phore). In a broad perspective, this work showcases the idea of secondary group participation (SGP) in the construction of coordination networks, an idea that parallels that of hemilabile ligands in organometallics and points to an effective strategy in developing advanced functions in solid state framework materials

Arylgold(I) Complexes from Base-Assisted Transmetalation: Structures, NMR Properties, and Density-Functional Theory Calculations

The synthesis of gold­(I) complexes of the type LAuR (L = PCy₃, IPr; R = aryl; IPr = 1,3-bis­(2,6-diisopropylphenyl)­imidazol-2-ylidene) starting from LAuX (X = Br, OAc) and boronic acids in the presence of Cs₂CO₃ has been investigated. The reactions proceed smoothly in good to excellent yields over the course of 24–48 h in isopropyl alcohol at 50–55 °C. The aryl groups include a variety of functionalities and steric bulk, and in two cases, are heterocyclic. All of the products have been characterized by multinuclear NMR spectroscopy and elemental analysis and most by X-ray crystallography. This work affirms that, almost without exception, base-assisted auration is a useful and reliable way to form gold–carbon bonds

Arylgold(I) Complexes from Base-Assisted Transmetalation: Structures, NMR Properties, and Density-Functional Theory Calculations

The synthesis of gold­(I) complexes of the type LAuR (L = PCy₃, IPr; R = aryl; IPr = 1,3-bis­(2,6-diisopropylphenyl)­imidazol-2-ylidene) starting from LAuX (X = Br, OAc) and boronic acids in the presence of Cs₂CO₃ has been investigated. The reactions proceed smoothly in good to excellent yields over the course of 24–48 h in isopropyl alcohol at 50–55 °C. The aryl groups include a variety of functionalities and steric bulk, and in two cases, are heterocyclic. All of the products have been characterized by multinuclear NMR spectroscopy and elemental analysis and most by X-ray crystallography. This work affirms that, almost without exception, base-assisted auration is a useful and reliable way to form gold–carbon bonds

Immobilization of Volatile and Corrosive Iodine Monochloride (ICl) and I₂ Reagents in a Stable Metal–Organic Framework

The major discovery here is a robust and water-stable metal–organic framework (MOF) material capable of reversible binding of the volatile and reactive molecules of ICl and I₂. The immobilization of I₂ and ICl, as well as their controllable release thus achieved, is to facilitate the wide-ranging applications of these volatile species as catalysts and reagents in chemical and industrial processes. The framework material TMBP·CuI (hereafter TCuI) can be conveniently prepared in quantitative yields by heating CuI and the organic linker TMBP (3,3′,5,5′-tetramethyl-4,4′-bipyrazol) in acetonitrile. The microporous three-dimensional net of TCuI features CuI chains that contribute to efficient and reversible binding of ICl and I₂ molecules, to result in the stoichiometrically well-defined adducts of TCuI·ICl and TCuI·I₂, respectively. Moreover, the confinement of a volatile compound like ICl within the MOF medium provides unique opportunities to enhance its reactivity and selectivity as a chemical reagent, as is exemplified by the iodination reactions examined herein. With this exemplary study, we intend to stimulate interest in further exploring MOFs and other porous media (e.g., porous polymers) for entrapping ICl and other volatile reagents (e.g., Br₂, SCl₂, S₂Cl₂, and SOCl₂) and for potentially novel reactivity associated with the porous medium

High Nuclearity Assemblies and One-Dimensional (1D) Coordination Polymers Based on Lanthanide–Copper 15-Metallacrown‑5 Complexes (Ln^III = Pr, Nd, Sm, Eu)

Complexes {[LnCu₅(GlyHA)₅(<i>m</i>-bdc)­(H₂O)_4–<i>x</i>]₂[LnCu₅(GlyHA)₅(SO₄)­(<i>m</i>-bdc)­(H₂O)₄]₂}·(30 + 2<i>x</i>)­H₂O (where GlyHA^2– = glycinehydroxamate, <i>m</i>-bdc^2– = <i>m</i>-phthalate; Ln = Pr and <i>x</i> = 0.21 for compound <b>1</b>, or Ln = Sm and <i>x</i> = 0.24 for <b>3</b>) and one-dimensional (1D) coordination polymers {[NdCu₅(GlyHA)₅(H₂O)₅(<i>m</i>-bdc)]<i>_nn</i>[NdCu₅(GlyHA)₅(H₂O)₄(μ-CO₃)­(<i>m</i>-bdc)]}·13<i>n</i>H₂O (<b>2</b>) and {[EuCu₅(GlyHA)₅(H₂O)₃]­(<i>m</i>-bdc)₂[EuCu₅(GlyHA)₅(<i>m</i>-bdc)­(H₂O)₃]}_<i>n</i>·17<i>n</i>H₂O (<b>4</b>) were obtained starting from the 15-metallacrown-5 complexes {[LnCu₅(GlyHA)₅(SO₄)­(H₂O)_6.5]}₂(SO₄)·6H₂O (Ln = Pr, Nd, Sm, Eu) by the partial or complete metathesis of sulfate anions with <i>m</i>-phthalate. Compounds <b>1</b> and <b>3</b> contain unprecedented quadruple-decker neutral metallacrown assemblies, where the [LnCu₅(GlyHA)₅]³⁺ cations are linked by <i>m</i>-phthalate dianions. In contrast, in complexes <b>2</b> and <b>4</b>, these components assemble into 1D chains of coordination polymers, the adjacent {[NdCu₅(GlyHA)₅(H₂O)₅(<i>m</i>-bdc)]⁺}<i>_n</i> 1D chains in <b>2</b> being separated by discrete [NdCu₅(GlyHA)₅(H₂O)₄(μ-CO₃)­(<i>m</i>-bdc)]}⁻ complex anions. The crystal lattices of <b>2</b> and <b>4</b> contain voids filled by solvent molecules. Desolvated <b>4</b> is able to absorb up to 0.12 cm³/g of methanol vapor or 0.04 cm³/g of ethanol at 293 K. The isotherm for methanol absorption by compound <b>4</b> is consistent with a possible “gate opening” mechanism upon interaction with this substrate. The χ_M<i>T</i> vs <i>T</i> data for complexes <b>1</b>–<b>4</b> and their simpler starting materials {[LnCu₅(GlyHA)₅(SO₄)­(H₂O)_6.5]}₂(SO₄)·6H₂O (Ln­(III) = Pr, Nd, Sm, Eu) were fitted using an additive model, which takes into account exchange interactions between lanthanide­(III) and copper­(II) ions in the metallamacrocycles via a molecular field model. The exchange interactions between adjacent Cu­(II) ions in metallacrown fragments were found to fall in the range of −47 < <i>J</i>_Cu–Cu < −63 cm^–1. These complexes are the first examples of a Ln­(III)-Cu­(II) 15-metallacrowns-5 (Ln­(III) = Pr, Nd, Sm, Eu), for which values of exchange parameters have now been reported

Convenient Detection of Pd(II) by a Metal–Organic Framework with Sulfur and Olefin Functions

A highly specific, distinct color change in the crystals of a metal–organic framework with pendant allyl thioether units in response to Pd species was discovered. The color change (from light yellow to orange/brick red) can be triggered by Pd species at concentrations of a few parts per million and points to the potential use of these crystals in colorimetric detection and quantification of Pd­(II) ions. The swift color change is likely due to the combined effects of the multiple functions built into the porous framework: the carboxyl groups for bonding with Zn­(II) ions to assemble the host network and the thioether and alkene functions for effective uptake of the Pd­(II) analytes (e.g., via the alkene–Pd interaction). The resultant loading of Pd (and other noble metal) species into the porous solid also offers rich potential for catalysis applications, and the alkene side chains are amenable to wide-ranging chemical transformations (e.g., bromination and polymerization), enabling further functionalization of the porous networks

Convenient Detection of Pd(II) by a Metal–Organic Framework with Sulfur and Olefin Functions

A highly specific, distinct color change in the crystals of a metal–organic framework with pendant allyl thioether units in response to Pd species was discovered. The color change (from light yellow to orange/brick red) can be triggered by Pd species at concentrations of a few parts per million and points to the potential use of these crystals in colorimetric detection and quantification of Pd­(II) ions. The swift color change is likely due to the combined effects of the multiple functions built into the porous framework: the carboxyl groups for bonding with Zn­(II) ions to assemble the host network and the thioether and alkene functions for effective uptake of the Pd­(II) analytes (e.g., via the alkene–Pd interaction). The resultant loading of Pd (and other noble metal) species into the porous solid also offers rich potential for catalysis applications, and the alkene side chains are amenable to wide-ranging chemical transformations (e.g., bromination and polymerization), enabling further functionalization of the porous networks

Single-Crystalline UiO-67-Type Porous Network Stable to Boiling Water, Solvent Loss, and Oxidation

With methylthio groups flanking the carboxyl groups, the 3,3′,5,5′-tetrakis­(methylthio)­biphenyl dicarboxylate (TMBPD) linker forms a zirconium­(IV) carboxylate porous framework featuring the topology of the UiO-67 prototype, i.e., with a face-centered-cubic array of the Zr₆O₄(OH)₄ clusters. Thioether functionalization proves valuable because the ZrTMBPD crystal is found to be exceptionally stable not only upon long-term exposure to air but also in boiling water and a broad range of pH conditions. The hydrophobicity of the metal–organic framework can also be tuned by simple H₂O₂ oxidation, as illustrated in the water contact-angle measurement of the pristine and H₂O₂-treated ZrTMBPD solid

Fluoride Complexes of Cyclometalated Iridium(III)

Many electroluminescent devices rely on cyclometalated iridium­(III). Their advancement depends on access to reactive starting materials because of the inertness of Ir­(III). Notably, fluoride complexes of bis­(cyclometalated) Ir­(III) are scarce. Syntheses of bridged and terminal fluorides are reported here. New compounds are luminescent and thermally reactive; they are characterized by ground-state and optical methods. Crystal structures were determined for one bridging and one terminal fluoride complex. The terminal fluoride shows intramolecular hydrogen bonding to an adjacent 3,5-dimethylpyrazole ligand; a lesser interaction may occur between F and a nearby aromatic C–H bond. Terminal fluoride complexes react with carbon-, silicon-, and sulfur-based electrophiles. The new complexes phosphoresce with microsecond lifetimes at 77 and 298 K. Density-functional theory calculations indicate triplet states with little contribution from fluoride. The compounds herein are versatile phosphors having the ground-state reactivity of late transition metal fluorides

Fluoride Complexes of Cyclometalated Iridium(III)

Many electroluminescent devices rely on cyclometalated iridium­(III). Their advancement depends on access to reactive starting materials because of the inertness of Ir­(III). Notably, fluoride complexes of bis­(cyclometalated) Ir­(III) are scarce. Syntheses of bridged and terminal fluorides are reported here. New compounds are luminescent and thermally reactive; they are characterized by ground-state and optical methods. Crystal structures were determined for one bridging and one terminal fluoride complex. The terminal fluoride shows intramolecular hydrogen bonding to an adjacent 3,5-dimethylpyrazole ligand; a lesser interaction may occur between F and a nearby aromatic C–H bond. Terminal fluoride complexes react with carbon-, silicon-, and sulfur-based electrophiles. The new complexes phosphoresce with microsecond lifetimes at 77 and 298 K. Density-functional theory calculations indicate triplet states with little contribution from fluoride. The compounds herein are versatile phosphors having the ground-state reactivity of late transition metal fluorides