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We placed nanometer-scale water-tube clusters with phase transition within a porous crystal formed from molecular blocks specifically designed to investigate the molecular dynamics of confined water molecules.

The unique strength, directionality, and complementarity of noncovalent interactions such as hydrogen bonding and coordination bonding play a central role in the creation of a variety of molecular architectures for molecular self-assembly and recognition in chemical, physical, and biological sciences. [1, 2] The building blocks possessing such noncovalent interaction sites can produce one-, two-, and three-dimensional molecular arrangements with long-range order. [3±5] Control of such multidimensional molecular arrangements is essential for progressing crystal engineering and in constructing the desired molecular-based materials. [6±8] We have designed a new anionic building block, a tris(biimidazolato)nickel(ii) complex, in which the three strong, p-conjugated biimidazolate ligands each provide one complementary hydrogen-bonding site. We now report the construction of four types of hydrogen-bonded and coordination-bonded molecular architectures of nickel(ii) ions, biimidazolate ligands, and counter cations.Since 2,2'-biimidazole (H 2 bim) is a bidentate chelating ligand with multiple proton-donor sites, it can coordinate to a transition metal in three reversible protonated and deprotonated modes: neutral (H 2 bim), monoanionic (Hbim À1 ), and dianionic (bim À2 ). [9] The mono-deprotonated ligand (Hbim À1 ) can form both a complementary binary NH´´´N-type hydrogen bond and a coordination bond with metal ions (see structure A). [10] In this study, we have found that simple one-pot procedures [11] of mixing the nickel(ii) ions, Hbim À1 , and counter cations produces four types of hydrogen-bonded crystals (1 ± 4) based on arrangements of the [Ni(Hbim) 3 ] À building blocks ( Figure 1). Figures 2 and 3 show the schematic drawings and crystal structures of the four types of molecular arrangements. Figure 1. L and D isomers of the building block [Ni(Hbim) 3 ] À . d) expanded 2D honeycomb sheet b) 1D zigzag ribbon c) 2D honeycomb sheet a) 0D dot Figure 2. Schematic representations of the hydrogen-bonded networks of [Ni(Hbim) 3 ] À building blocks for 1 ± 4 (a ± d). Water molecules (*) and free 2,2'-biimidazole (*) also function as intermediate spacers.As a common feature, all the structures contain the anionic building block [Ni(Hbim) 3 ] À , in which the central Ni II atom is coordinated by three bidentate Hbim À ligands through the lone pairs of the imine nitrogen atoms in the imidazole rings. The NiÀN bond lengths are in the range of 1.96(3) ± 2.19(2) . The building block has approximate D 3 symmetry; both the D and L isomers are illustrated in Figure 1.Structure 1 [12a] contains tetramethylammonium as the counter cation (Figures 2 a, 3 a). Although there is no hydrogen bonding between the ligands of the [Ni(Hbim) 3 ] À building blocks, the units are connected by hydrogen bonding through water molecules to make a sheet arrangement along the ab plane (Figure 2 a): The length of the hydrogen bonds between the oxygen atoms of the water molecules and the nitrogen atoms of the Hbim À ligands are 2.753(4) and 2.756(4) ...

No abstract

Oligoacenes are of interest as organic p-type semiconductors for use in electronic devices, but their use as n-type semiconductors is limited. N-Heteroacenes have been investigated as oligoacene-based n-type semiconductors due to their enhanced electron affinity. Herein, we report the synthesis, X-ray crystal structures, electrochemical, and field-effect transistor properties of TANC and BTANC.

Heterodinucleating macrocycles with two 2,6-bis(iminomethyl)-4-methylphenolate entities combined through two lateral chains, -(CHz):and -(CH2)mNH(CH2)m-(m = 2,3), at the imino nitrogens have been prepared as CunPbn complexes of the formula [CuPb(L)]XY (L2~= LI for m = 2 and L2 for m = 3; XY = (C104)2, (NOjHPFe), (AcO)(BPh4)). [CuPb(Ll)](AcO)(BPh4)»DMF crystallizes in the monoclinic crystal system, space group P2\/n, with Z = 4, a = 18.890(3) A, b = 19.968(3) A, c = 12.704(2) A, ß « 91.61(1)°, and F= 4790(1) A3. The refinement converges with R = 0.0697 and Fw = 0.0863 for 4945 reflections with |F0| > 3a(|Fo|). The crystal consists of a dimeric cation {CuPb(Ll)(Ac)}22+ bridged by acetate groups, tetraphenylborate ions, and DMF molecules. The Cu is located at the 4-coordination site formed with the ethylene chain and assumes a planar environment. The Pb is at the 5-coordination site formed with the -(CH2)2NH(CH2)2-chain and assumes an eight-coordinate structure also involving three acetate oxygen atoms. The Cu--Pb separation, bridged by two phenolic oxygens, is 3.577(2)A. In the crystal, the dimeric cations further interact through out-of-plane bonding between the {CUN2O2} entities forming a column along the a axis. The [CuPb(Ll)]XY complexes react with metal(II) sulfates to form a series of CunMn complexes, [CuM(Ll)]XY (M = Mn, Fe, Co, Ni, Cu, Zn). [CuMn(Ll)](AcO)(BPh4) crystallizes in the monoclinic space group F2i/n, withZ = 4, a = 17.508(8) A, b = 15.539(5) A, c = 16.515(5) A,j8 = 106.30(3)°, and V = 4312(3) A3. The refinement converges with R = 0.0689 and Rw = 0.0563 for 2935 reflections with |F 3a(|F0|). The Cu(II) and Mn(II) ions reside at the 4and 5-coordination sites of the macrocycle, respectively, and the acetate group bridges the two metal ions providing a nearly square-pyramidal geometry for the Cu and a highly distorted six-coordinate environment for the Mn. The Cu--Mn separation is 3.122(2) A. The cryomagnetic investigations (4.2-300 K) for the CuMn, CuFe, CuCo, CuNi, and CuCu complexes reveal the operation of an antiferromagnetic spin-exchange interaction within each molecule. The cyclic voltammograms of the CuM complexes show Cu(II)/Cu(I) reduction near -0.8 V (vs SCE) and oxidation at the ligand center near +1.3 V. The oxidation of the Fe(II) of the CuFe complex occurs at +0.64 V whereas the Mn(II) ion of the CuMn complex and the Co(II) ion of the CuCo complex are hardly oxidized.

The dinucleating macrocycles H,L"" containing two 2,6-di(aminomethyl) -4-methylphenol entities combined through two alkane chains, (CH,), and (CH,),, at the amine nitrogens have been prepared for the (m,n) sets (2,3), (2,4), (2,5), (3,3) and (3,4). The dinuclear copper(l1) complexes having general formula [Cu,L"',"] [CIO,], have been prepared. Cryomagnetic investigations (80-300 K) reveal a strong antiferromagnetic spin-exchange between the copper( it) ions within each complex (J based on X' = -W S J , in the range -345 to -255 cm-l). The cyclic voltammograms show two reduction couples, Cu"Cu"-CuCu" and CulCu"-Cu'Cu'. The comproportionation constants K,, for the mixedvalence Cu'Cu" complexes have been determined electrochemically. The Kcom value increase in the order of the macrocycles ( L292-< ( L2s4), < ( L2,,), and ( L3p3),-< ( L392-. The Cu'Cu" mixed-valence state is shown to be 'spin-trapped' (Class I) for all the complexes based on ESR spectra.

Di‐Re straits: Synchronized motion of protons and electrons, as shown in the scheme, has been observed in a hydrogen‐bonded Re dimer complex. The mixed‐valence states obtained by electrochemical redox reactions are stabilized by proton transfer within the dual hydrogen‐bonding site between 2,2′‐biimidazolate ligands.