Highly Elastic Organic Crystals for Flexible Optical Waveguides

The study of elastic organic single crystals (EOSCs) has emerged as a cutting‐edge research of crystal engineering. Although a few EOSCs have been reported recently, those suitable for optical/optoelectronic applications have not been realized. Here, we report an elastic crystal of a Schiff base, (E)‐1‐(4‐(dimethylamino)phenyl)iminomethyl‐2‐hydroxyl‐naphthalene. The crystal is highly bendable under external stress and able to regain immediately its original straight shape when the stress is released. It displays bright orange–red emission with a high fluorescence quantum yield of 0.43. Intriguingly, it can serve as a low‐loss optical waveguide even at the highly bent state. Our result highlights the feature and utility of “elasticity” of organic crystals.     

Lattice models of hydrogen-bonded solvents. II

We consider a lattice model of a binary mixture in which each molecule of one component can form zero, one, or two bonds to molecules of the same species on neighboring vertices of the square lattice. We allow the energy of molecules with two bonds to depend on the valence angle, thus generalizing the first paper in this series. If straight polymeric configurations are favored over all others, then a phase transition occurs for low enough temperature. On the other hand, if bent configurations are favored, there is no phase transition. Analogous results are obtained for the hexagonal lattice, where we distinguish energetically betweencis andtrans isomerism of four bonded molecules.Supported by the Danish Science Foundation under grant 511-3635.     

Structure of {Pb[S2CN(C2H5)2]2(1,10-phenanthroline)}2

Lead (II) nitrate reacts with 1,10-phenanthroline and sodium diethyldithiocarbamate in water to produce yellow bisdiethyldithiocarbamata 1,10-phenanthroline lead(II). Crystals from water are triclinic, space group $P\bar 1$ (#2),a=10.53(2) Å,b=11.050(12)Å,c=24.74 (3) Å, α=94.71 (9)⁰, β=98.15(11)^o, γ=114.11(9)^o,V=2569(6) ų,Z=2. Each lead atom has approximate pentagonal pyramid coordination geometry through the nitrogens of a phenathroline and sulfurs of two dithiocarbamates. Additionally, complexes form loose dimers in which lead atoms are weakly coordinated to a sulfur in an adjacent complex. IR and proton nmr spectrum of the complex are consistent with the solid state structure.     

Heavy metal complexes of macrocyclic trithioethers

We report here two crystal structures of heavy metal complexes containing macrocyclic trithioethers. The trithioether, 10S3 (1,4,7-trithiacyclodecane) complexes Pb(II) to form a compound of the formula [Pb(10S3)](ClO₄)₂(H₂O) (Compound 1). This behavior contrasts the related trithioether 9S3 (1,4,7-trithianonane), which readily forms a bis Pb(II) complex. Crystals of Compound 1 consist of [Pb(10S3)(H₂O)]²⁺ units and perchlorate anions which are weakly bound to the Pb²⁺ center. The two perchlorate anions serve as bidentate ligands to a single lead(II) center. However, a third oxygen in one of the perchlorates also serves as a bridging group between two lead(II) centers, linking the [Pb(10S3)(H₂O)]²⁺ units into zigzag chains. Thus, a highly irregular nine-coordinate (S₃O₆) environment around the Pb²⁺ion is formed by the three sulfur donors from the 10S3 ligand, one coordinated water, and five oxygens from three different perchlorate anions. Also, the lone pair electrons on the Pb center are stereochemically active. Compound 2, [Cd(9S3)₂](ClO₄)₂ 2 CH₃NO₂, forms a distorted octahedral structure with unusual hexakis(thioether) coordination to the Cd(II) center. Bond distances and angles are very comparable to those found in the structure of the tetrafluoroborate salt of the complex cation. (1): P2₁/c, a = 9.1720(6) Å, b = 15.7687(11) Å, c = 11.8427(8) Å, = 93.0180(10) , V = 1710.4 (2) ų, Z = 4; (2): P2₁/c , a = 10.4305(10) Å, b = 15.2059(6) Å, c = 9.4919(7) Å, = 99.324(9), V = 1485.6(2) ų, Z = 2.     

Growth of NaBi(WO4)2 crystal by modified-Bridgman method

NaBi(WO₄)₂ (NBW) crystals have been grown for the first time by modified-Bridgman method. Influences of some factors on the crystal growth process are discussed. X-ray powder diffraction experiments show that the unit cell parameters of NBW crystal are a=b=0.5284 nm, c=1.1517 nm, and V=0.3215 nm³. The differential thermal analysis shows that the NBW crystal melts at 923°C.     

Structure and properties of a heterocomplex compound based on lead(II) hexafluoroacetyl acetonate and copper(II) trifluoroacetyl acetonate Cu(tfa)2·Pb(hfa)2

The crystals of a heterobimetallic complex based on lead(II) hexafluoroacetyl acetonate and copper(II) trifluoroacetyl acetonate were investigated by X-ray diffraction. Crystal data for Cu(tfa)₂·Pb(hfa)₂: a = 9.3991(4) Å, b = 11.7816(5) Å, c = 13.9736(5) Å, α = 88.311(2)°, β = 89.972(1)°, γ = 76.326(1)°, space group P-1, Z = 2, d _calc = 2.190 g/cm³. The basic structural motif for the complexes is coordination polymer in the form of chains of alternating complex molecules. The Cu(tfa)₂ molecules have a trans configuration. The results of a DTA-TG analysis of the compound are given.