Monomeric Molecular Structure Research Articles

Effect of selenophene in naphthalene-diimide-vinylene-based small molecules on n-type organic field-effect transistors

Abstract Two naphthalene diimide (NDI)-based small molecules, one with a thiophene-vinylene-thiophene linker donor unit (N-TVT-N) and the other with a selenophene-vinylene-selenophene linker donor unit (N-SVS-N), were newly synthesized for the purpose of serving as the active materials of n-type organic field-effect transistors (OFETs). We investigated the various characteristics of the synthesized small molecules to study how the type of donor unit would affect the charge transport of the resulting thin film. The monomeric molecular structure of N-SVS-N, i.e., that with selenium (Se) substituted for sulfur, was found to be tilted about twice as much as that of N-TVT-N, and to display lower backbone planarity. Unexpectedly, the thin films of N-SVS-N each showed a smoother and more uniform surface morphology and predominantly edge-on orientation in comparison with those of N-TVT-N. As the result, the optimally annealed OFETs containing N-SVS-N and N-TVT-N exhibited electron mobilities of up to 0.016 cm2 V−1 s−1 and 6.6 × 10−3 cm2 V−1 s−1, respectively. These results could be explained by the structural features of N-SVS-N facilitating interactions between the electron-rich selenophenes.

Solvent-assisted monomeric molecular structure of the phosphate diester and the synthesis of menthol-based phosphate diesters

Phosphate diesters are well known to form intermolecular H-bonded dimeric structures in their solid-state. Recently, we reported 2,6-(CHPh)2-4-iPr-phenyl substituted phosphate diester exists as H-bonded monomeric molecular structure along with water dimer in the solid-state. Herein we report 2,6-(CHPh)2-4-iPr-phenyl substituted phosphate diester forms a monomeric molecular structure in the solid-state upon co-crystallization with dimethylformamide, DMF (Me2NCHO). The -CHO group of DMF simultaneously acts as an H-bond acceptor to P-OH and an H-bond donor to P=O moieties. We also used the alcohols, ROH (R = Me, Et, iPr, and tBu), for crystallisation of 2,6-(CHPh)2-4-iPr-phenyl substituted phosphate diester. In these instances, solvent-incorporated dimeric structures are found in the solid-state. We also report the syntheses and molecular structures of anionic phosphate diesters of 2,6-(CHPh)2-4-iPr-phenyl substituted phosphate diester possessing various counter cations. Moreover, we also report the syntheses and molecular structures of phosphate diesters based on (−)-menthol, (+)-menthol and (+)/(−)-menthol. These exist as H-bonded dimers in the solid-state. Herein we report 2,6-(CHPh)2-4-iPr-phenyl substituted phosphate diester forms a monomeric molecular structure in the solid-state upon co-crystallization with dimethylformamide, DMF (Me2NCHO). The -CHO group of DMF simultaneously acts as an H-bond acceptor to P-OH and an H-bond donor to P=O moieties.

Crystal structure and quantum-chemical calculations of a tri-methyl-aluminium-THF adduct.

The title compound, trimeth-yl(tetra-hydro-furan-κO)aluminium(III), [Al(CH3)3(C4H8O)], is an addition product of tri-methyl-aluminium and tetra-hydro-furan (THF). Instead of a dimeric structure, which is very common for these types of compounds, a monomeric mol-ecular structure is observed. The C-Al-C angles in the mol-ecule are very different from the C-Al-C angles found in dimeric mol-ecular structures, leading to a different symmetry around the AlIII atom. The reasons for these differences are discussed.

Monomeric siliconthiodichloride trapped by a Lewis base.

Thiophosgene (CSCl2), a chemical reagent used in numerous organic syntheses, exists in the monomeric form while its heavier silicon analogue [siliconthiodichloride (SiSCl2)] has been isolated so far as a dimer at room temperature and as a tetramer at 180 °C. Herein, we report on the first synthesis, isolation, and characterization of cyclic alkyl(amino) carbene (cAAC) stabilized siliconthiodichloride (cAAC)SiSCl2 (3) in the neutral monomeric form. 3 is synthesized via reaction of (cAAC˙)2Si2Cl4 (1) or (cAAC)2Si2Cl2 (2) with S8 in the temperature range of -78 to 20 °C. An NHC [NHC = N-heterocyclic carbene] analogue of 3 is not isolated when (NHC)SiCl2 is reacted with S8. The bright yellow colored compound 3 is soluble in polar organic solvents. It is stable at room temperature for a month under an inert atmosphere. 3 decomposes above 160 °C. The monomeric molecular structure of 3 has been unambiguously confirmed by X-ray single crystal diffraction. 3 is also characterized by NMR, UV-vis, and IR spectroscopy. The bonding and electron density distributions of 3 have been further studied by theoretical calculations.

Sulfur Donor Atom Effects on Copper(I)/O2 Chemistry with Thioanisole Containing Tetradentate N3S Ligand Leading to μ-1,2-Peroxo-Dicopper(II) Species

To better understand the effect of thioether coordination in copper-O(2) chemistry, the tetradentate N(3)S ligand L(ASM) (2-(methylthio)-N,N-bis((pyridin-2-yl)methyl)benzenamine) and related alkylether ligand L(EOE) (2-ethoxy-N,N-bis((pyridin-2-yl)methyl)ethanamine) have been studied. The corresponding copper(I) complexes, [(L(ASM))Cu(I)](+) (1a) and [(L(EOE))Cu(I)](+) (3a), were studied as were the related compound [(L(ESE))Cu(I)](+) (2a, L(ESE) = (2-ethylthio-N,N-bis((pyridin-2-yl)methyl)ethanamine). The X-ray structure of 1a and its solution conductivity reveal a monomeric molecular structure possessing thioether coordination which persists in solution. In contrast, the C-O stretching frequencies of the derivative Cu(I)-CO complexes reveal that for these complexes, the modulated ligand arms, whether arylthioether, alkylthioether, or ether, are not coordinated to the cuprous ion. Electrochemical data for 1a and 2a in CH(3)CN and N,N-dimethylformamide (DMF) show the thioanisole moiety to be a poor electron donor compared to alkylthioether (1a is ∼200 mV more positive than 2a). The structures of [(L(ASM))Cu(II)(CH(3)OH)](2+) (1c) and [(L(ESE))Cu(II)(CH(3)OH)](2+) (2c) have also been obtained and indicate nearly identical copper coordination environments. Oxygenation of 1a at reduced temperature gives a characteristic deep blue intermediate [{(L(ASM))Cu(II)}(2)(O(2)(2-))](2+) (1b(P)) with absorption features at 442 (1,500 M(-1) cm(-1)), 530 (8,600 M(-1) cm(-1)), and 605 nm (10,400 M(-1) cm(-1)); these values compare well to the ligand-to-metal charge-transfer (LMCT) transitions previously reported for [{(L(ESE))Cu(II)}(2)(O(2)(2-))](2+) (2b(P)). Resonance Raman data for [{(L(ASM))Cu(II)}(2)(O(2)(2-))](2+) (1b(P)) support the formation of μ-1,2-peroxo species ν(O-O) = 828 cm(-1)(Δ((18)O(2)) = 48), ν(sym)(Cu-O) = 547 cm(-1) (Δ((18)O(2)) = 23), and ν(asym)(Cu-O) = 497 cm(-1) (Δ((18)O(2)) = 22) and suggest the L(ASM) ligand is a poorer electron donor to copper than is L(ESE). In contrast, the oxygenation of [(L(EOE))Cu(I)](+) (3a), possessing an ether donor as an analogue of the thioether in L(ESE), led to the formation of a bis(μ-oxo) species [{(L(EOE))Cu(III)}(2)(O(2-))(2)](2+) (3b(O); 380 nm, ε ∼ 10,000 M(-1) cm(-1)). This result provides further support for the sulfur influence in 1b(P) and 2b(P), in particular coordination of the sulfur to the Cu. Thermal decomposition of 1b(P) is accompanied by ligand sulfoxidation. The structure of [{(L(EOE))Cu(II)(Cl)}(2)](+) (3c) generated from the reductive dehalogenation of organic chlorides suggests that the ether moiety is weakly bound to the cupric ion. A detailed discussion of the spectroscopic and structural characteristics of 1b(P), 2b(P), and 3b(O) is presented.

Synthesis and crystal structure of a novel luminescent cadmium complex

A novel cadmium complex Cd(IPA)2(phen)2 (IPAH = isophthanic acid, phen = 1,10-phenanthroline) was synthesized by hydrothermal methods and characterized structurally by X-ray diffraction. The complex possesses a monomeric molecular structure. Cd(IPA)2(phen)2 is orthorhombic, space group Aba2, with a = 14.670(7), b = 22.876(8), c = 9.473(6) Å, V = 3179(3) Å3, D c = 1.573 Mg m−3, Z = 4, F(000) = 1520, GOF = 1.027, R1 = 0.0299, wR2 = 0.0617. Photophysical properties (fluorescence excitation and emission spectra) are reported.

Syntheses and crystal structures of two novel lanthanide coordination compounds of 3-aminobenzoic acid

Two new lanthanide coordination compounds, RE(ABA)3(H2O)3·H2O (RE = Sm, Dy; ABA = 3-aminobenzoate), were obtained from ethanol solution and characterized structurally by X-ray diffraction methods. Both possess a monomeric molecular structure. Complex 1, Sm(ABA)3(H2O)3, is rhombohedral, space group R3c, with a = 18.999(3), c = 11.915(3) Å, V = 3724.6(12) Å3, D c = 1.784 Mg m−3, Z = 6, F(000) = 2010, GOF = 1.133 and R 1 = 0.0204. Complex 2, Dy(ABA)3(H2O)3, is isomorphous, with a = 18.956(4), c = 11.812(3) Å, V =3675.8(14) Å3, D c = 1.840 Mg m−3, Z = 6, F(000) = 2034 and R 1 = 0.0209. Photophysical properties of the complexes were investigated.

Direct Synthesis of Zinc and Nickel(II) Complexes with 1,4-Diazabicyclo[2.2.2]octane

Abstract The peculiarities of the formation of zinc and nickel(II) complexes by interaction of metal powder or metal oxide with ammonium salts (halides, nitrate, thiocyanate) were investigated in non-aqueous solutions (methanol, acetonitrile, N,N-dimethylformamide=DMF, dimethylsulfoxide=DMSO) in presence of 1,4-diazabicyclo[2.2.2]octane. The stoichiometry of the com ­ plexes was found to depend on the initial reagent ratio Ni/ZnO:NH4X and Ni/ZnO:Ten. The compounds of compositions Zn(HTen)(H2O)(NO3)3 and Ni(HTen)(Ten)Cl3 were character­ized by X-ray crystallography. Both complexes contain five-coordinate metal atoms. The zinc compound possesses monomeric molecular structure whilst the nickel complex is polymeric.

Preparation and crystal structure of the dicarboranyl-magnesium bis(dioxane) adduct Mg(2-Me-1,2-C 2B 10H 10) 2·2C 4H 8O 2

The preparation of Mg(2-Me-1,2-C 2B 10H 10) 2·2C 4H 8O 2 from the carboranyl Grignard reagent RMgBr (R = the methyl- ortho-carboranyl residue, 2-Me-1,2-C 2B 10H 10) by a dioxane-induced disproportionation reaction is described. An X-ray crystallographic study of the product has revealed a monomeric molecular structure R 2MgL 2 (L = 1,4-dioxane, C 4H 8O 2) in which the carboranyl groups and dioxane ligands provide the central magnesium atom with a distorted tetrahedral coordination sphere of two carbon and two oxygen atoms, with bond lengths MgC 2.156(5) Å, MgO 2.038(8) Å and bond angles CMgC 123.5(4)°, OMgO 99.5(5)°, distortions from regular tetrahedral angles attributable to the relative bulk of the carboranyl ligands.