Hydrogen bonded liquid crystalline heterodimers incorporating alkoxystilbazoles and alkoxy-4-pyridones

<div><p>The preparation and characterisation of a series of hydrogen bonded liquid crystalline dimers containing benzoic acid, alkanoic acid and phenol donors and alkoxy-stilbazole or alkoxy-4-pyridone hydrogen bond acceptors are reported. These heterodimers possess strong intermolecular donor–acceptor hydrogen bonding. The heterodimers, as well some of the individual components used in their preparation, possess liquid crystalline phases.</p></div

Synthesis of Ultrathin Films of Polyacrylonitrile by Photoinitiated Polymerization from Self-Assembled Monolayers on Gold^†

We report the synthesis of grafted polyacrylonitrile (PAN) brushes from alkanethiolate self-assembled monolayers (SAMs) on gold. The SAM consists of a dithiol-AIBN initiator that can be activated at room temperature by irradiation at 300 nm. The polymerizations were performed in DMF and yielded PAN films with a maximum thickness of ∼45 nm and a root mean square roughness of 0.17 nm after Soxhlet extraction. The static water contact angle was 55°, and the films were thermally stable after annealing at 105 °C for 3 days. The film thickness increased by 12% after annealing. The polymer films were characterized by reflection absorption infrared spectroscopy, contact angle measurements, and ellipsometry

Gold Nanoparticle Assemblies by Metal Ion−Pyridine Complexation and Their Rectified Quantized Charging in Aqueous Solutions

Gold nanoparticle assemblies were constructed by exploiting the complexation interactions between divalent metal ions and pyridine moieties. The thickness (layers) of the particle thin films was readily controlled by the repetition of the alternate dipping cycles, as monitored by quartz crystal microbalance (QCM). Electrochemical studies of these surface-immobilized nanoparticle layers revealed rectified quantized charging characters in aqueous solutions in the presence of hydrophobic anions. The effects of the nature of the electrolyte ions were investigated in the context of their hydrophobicity and interactions with the surface-bound particle molecules. It was found that the onset voltammetric potentials, as well as the effective molecular capacitance of the nanoparticles, were sensitive to the solution compositions. The behaviors were quite similar to those with the nanoparticle assemblies fabricated by dithiol linkages. The present study provided additional experimental parameters that could be used for the manipulation of nanoscale electron transfer

Synthesis and characterisation of laterally substituted noncentrosymmetric main chain hydrogen-bonded polymers

<div><p>A series of laterally substituted noncentrosymmetric hydrogen-bonded liquid crystalline polymers which incorporate stilbazole acceptor units, alkyl or ethylene glycol linkers units, and benzoic acid or phenol donor units were prepared and investigated for their hydrogen bonding behaviour and phase transitions. Fourier transform infrared (FTIR) indicated that these polymers possess strong intermolecular donor–acceptor hydrogen bonding. These polymers have lower melting points than their non-substituted analogue, and some of the polymers are mesomorphic.</p></div

Design and Investigation of a Series of Rhodamine-Based Fluorescent Probes for Optical Measurements of pH

A series of structurally similar fluorescent probes (1−4), synthesized from rhodamine B, were designed to optically measure pH. Each probe had a unique “off−on” response as the solution went from basic to acidic. Probes 1−3 exhibited a spirocyclic quenching of the pyronin B fluorophore, whereas probe 4 was quenched by PET from the amine moiety

Design and Investigation of a Series of Rhodamine-Based Fluorescent Probes for Optical Measurements of pH

A series of structurally similar fluorescent probes (1−4), synthesized from rhodamine B, were designed to optically measure pH. Each probe had a unique “off−on” response as the solution went from basic to acidic. Probes 1−3 exhibited a spirocyclic quenching of the pyronin B fluorophore, whereas probe 4 was quenched by PET from the amine moiety

Photoinduced Polymerization from Dimethylamino-Terminated Self-Assembled Monolayers on Gold

Photoinduced Polymerization from Dimethylamino-Terminated Self-Assembled Monolayers on Gol

Ferroelectric Liquid Crystals for Nonlinear Optics: Orientation of the Disperse Red 1 Chromophore along the Ferroelectric Liquid Crystal Polar Axis^†

Ferroelectric Liquid Crystals for Nonlinear Optics:  Orientation of the Disperse Red 1 Chromophore along the Ferroelectric Liquid Crystal Polar Axis†</sup

Ferroelectric Liquid Crystals for Nonlinear Optics: Orientation of the Disperse Red 1 Chromophore along the Ferroelectric Liquid Crystal Polar Axis^†

Ferroelectric Liquid Crystals for Nonlinear Optics:  Orientation of the Disperse Red 1 Chromophore along the Ferroelectric Liquid Crystal Polar Axis†</sup

pH-Dependent Si-Fluorescein Hypochlorous Acid Fluorescent Probe: Spirocycle Ring-Opening and Excess Hypochlorous Acid-Induced Chlorination

We report the synthesis and characterization of a fluorescent probe (Hypo-SiF) designed for the detection of hypochlorous acid (HOCl) using a silicon analogue of fluorescein (SiF). The probe is regulated in an “off–on” fashion by a highly selective thioether spirocyclic nonfluorescent structure that opens to form a mixture of fluorescent products in the presence of HOCl. Over a range of pH values, the probe reacts with a stoichiometric amount of HOCl, resulting in a mixture of two pH-dependent fluorescent species, a SiF disulfide product and a SiF sulfonate product. The unique colorimetric properties of the individual SiF fluorophores were utilized to perform simultaneous detection of HOCl and pH. When an excess of HOCl is present, the SiF fluorophores become chlorinated, via an intermediate halohydrin, resulting in a more pH independent and red-shifted fluorophore