Rotaxanated conjugated sensory polymers

Two highly emissive conjugated polymers with tethered rotaxane repeat units are reported. Hydrogen bonding between acidic alcohols and the N-heteroaromatic groups in the rotaxanes attenuates polymer fluorescence. In addition, the rotaxane groups create precise three-dimensional pockets for metal binding, which results in fluorescence quenching. Exposing thin films of Zn-doped polymers to alcohol vapors reverses the quenching by up to 25%.     

Coordination Compounds of Schiff-Base Ligands Derived from Diaminomaleonitrile (DMN): Mononuclear, Dinuclear, and Macrocyclic Derivatives

Copper(II) and V(IV)O complexes of an open chain (1:2) Schiff-base ligand (H(2)L1), derived by the template condensation of diaminomaleonitrile (DMN) and salicylaldehyde, and dicopper(II) complexes of (2:2) macrocyclic Schiff-base ligands derived by template condensation of diformylphenols and diaminomaleonitrile, have been synthesized and studied. Structures have been established for the first time for mononuclear Cu(II) and V(IV)O derivatives of the open chain ligand H(2)L1 (1:2), a dinuclear macrocyclic Cu(II) complex derived from a 2:2 macrocyclic ligand (H(2)M1), and the half-condensed 1:1 salicylaldehyde ligand (H(2)L2). [Cu(L1)] (1) (L1 = C(18)H(10)N(4)O(2)) crystallized in the monoclinic system, space group P2(1)/n (No. 14), with a = 11.753(6) ?, b = 7.708(5) ?, c = 16.820(1) ?, and Z = 4. [VO(L1)(DMSO] (2) crystallized in the orthorhombic system, space group Pbca (No. 61), with a = 22.534(9) ?, b = 23.31(1) ?, c = 7.694(5) ?, and Z = 8. H(2)L2 (C(18)H(8)N(4)O) (3) crystallized in the monoclinic system, space group P2(1)/c (No. 14), with a = 13.004(6) ?, b = 11.441(7) ?, c = 7.030(4) ?, and Z = 4. [Cu(2)(M3)](CH(3)COCH(3)) (4) (M3 = C(32)H(24)N(8)O(4)) crystallized in the monoclinic system, space group C2/c (No. 15), with a = 38.33(2) ?, b = 8.059(4) ?, c = 22.67(2) ?, and Z = 8. [Cu(L3)(DMSO)] (5) (L3 = C(20)H(14)N(2)O(4)) crystallized in the triclinic system, space group P&onemacr; (No. 2), with a = 10.236(4) ?, b = 13.514(4) ?, c = 9.655(4) ?, and Z = 2. 4 results from the unique addition of two acetone molecules to two imine sites in [Cu(2)(M1)](ClO(4))(2) (M1 = 2:2 macrocyclic ligand derived from template condensation of DMN and 2,6-diformyl-4-methylphenol). 4 has extremely small Cu-OPh-Cu bridge angles (92.0, 92.8 degrees ), well below the expected lower limit for antiferromagnetic behavior, but is still antiferromagnetically coupled (-2J = 25.2 cm(-)(1)). This behavior is associated with a possible antiferromagnetic exchange term that involves the conjugated framework of the macrocyclic ligand itself. The ligand L3 in 5 results from hydrolysis of M1 on recrystallization of [Cu(2)(M1)](ClO(4))(2) from undried dimethyl sulfoxide.     

Host–Guest Chemistry Within Cellulose Nanocrystal Gel Receptors

Cellulose nanocrystals (CNCs) spontaneously assemble into gels when mixed with a polyionic organic or inorganic salt. Here, we have used this ion-induced gelation strategy to create functional CNC gels with a rigid tetracationic macrocycle, cyclobis(paraquat-p-phenylene) ( CBPQT ⁴⁺). Addition of [ CBPQT ]Cl₄ to CNCs causes gelation and embeds an active host inside the material. The fabricated CNC gels can reversibly absorb guest molecules from solution then undergo molecular recognition processes that create colorful host–guest complexes. These materials have been implemented in gel chromatography (for guest exchange and separation), and as elements to encode 2- and 3-dimensional patterns. We anticipate that this concept might be extended to design a set of responsive and selective gel-like materials functioning as, for instance, water-pollutant scavengers, substrates for chiral separations, or molecular flasks.     

Weak localization and electron-electron interactions in thin Pd and PdHx films

We investigate the temperature and magnetic field dependence of the resistance R of thin Pd and PdHx films. We show that the logarithmic behaviour R(T) ≈ A ln T is dominated in Pd by the interaction effect. Loading progressively with hydrogen shows first no change in A and then a decrease followed by a sign reversal when superconducting fluctuations prevail. The application of a magnetic field restores then a positive and large value of A. These data are analyzed within recent theories.     

Three-component bimetallic (Pd/In) mediated cascade allylation of C=X functionality: Part 1. Scope and Class 1 examples with aldehydes and ketones

A new general three-component Pd/In bimetallic cascade reaction with four synthetic variants involving aryl iodides, allenes and C=X compounds affording homoallylic alcohols/amines as products is described and exemplified for Class 1 processes (intermolecular Pd-intermolecular In steps). Remarkable increases in yield and reaction rates were observed in the presence of amine additives. Excellent diastereoselection is exhibited when 2-hydroxycyclohexanone is employed, and semi-empirical and ab initio calculations are used to rationalise the observed syn:anti diastereoselectivity.     

Photonic Patterns Printed in Chiral Nematic Mesoporous Resins

Chiral nematic mesoporous phenol‐formaldehyde resins, which were prepared using cellulose nanocrystals as a template, can be used as a substrate to produce latent photonic images. These resins undergo swelling, which changes their reflected color. By writing on the films with chemical inks, the density of methylol groups in the resin changes, subsequently affecting their degree of swelling and, consequently, their color. Writing on the films gives latent images that are revealed only upon swelling of the films. Using inkjet printing, it is possible to make higher resolution photonic patterns both as text and images that can be visualized by swelling and erased by drying. This novel approach to printing photonic patterns in resin films may be applied to anti‐counterfeit tags, signage, and decorative applications.     

Family of cadmium acetate coordination networks with structurally diverse [Cd4(OAc)9(μ3-OH)]2- secondary building units

By subtly varying crystallization conditions, four distinct cadmium acetate coordination networks with unit cell formulas Cd(87)(H(2)O)(36)(EtOH)(18)(OH)(12)(CH(3)CO(2))(162) (1), Cd(87)(H(2)O)(72)(OH)(12)(CH(3)CO(2))(162) (2), Cd(10)(H(2)O)(6)(OH)(2)(CH(3)CO(2))(18) (3), and Cd(20)(H(2)O)(20)(OH)(4)(CH(3)CO(2))(36) (4) have been isolated. The coordination networks exhibit interesting structural diversity and have been investigated by powder X-ray diffraction, elemental analysis, thermal gravimetric analysis, infrared spectroscopy, and single-crystal X-ray diffraction. All four complexes are composed of secondary building units with the general formula [Cd(4)(OAc)(9)(μ(3)-OH)](2-). Complexes 1 and 2 exhibit a remarkable three-dimensional network composed of aligned columns, each 4.5 nm long, containing three different cadmium acetate clusters. Complexes 3 and 4 extend in two-dimensions with each unit cell repeating a different linkage isomer of the [Cd(4)(OAc)(9)(μ(3)-OH)](2-) cluster.     

Campestarenes: novel shape-persistent Schiff base macrocycles with 5-fold symmetry

A simple 1-step procedure yields a family of easily modifiable, stable, conjugated Schiff base macrocycles with 5-fold symmetry mediated by 3-center hydrogen bonding.