Mesomorphic complexes through hydrogen bonding between alkoxy-substituted triarylmelamines and semiperfluorinated benzoic acids

The thermal behaviour of two 2,4,6-triarylamino-1,3,5-triazines carrying either three or six peripheral alkoxy chains have been investigated in binary mixtures with two-chain and three- chain partially fluorinated benzoic acids by means of polarizing microscopy, differential scanning calorimetry and X-ray scattering. The melamines form hydrogen-bonded aggregates with the complementary carboxylic acids. Each investigated equimolar mixture exhibits a hexagonal columnar mesophase. In the case of the six-fold alkoxy-modified triazine the individual columns are built up by descrete hetero-dimers with a circular cross-sectional shape. The segregation of fluorinated from lipophilic side chain regions leads to a superstructure within the hexagonal lattice. The hexagonal columnar phases of 1:1 compositions of the triazine, incorporating just three aliphatic chains with the semiperfluorinated benzoic acids, are formed by pairs of H-bonded dimeric supermolecules.     

Synthesis and Rh(I)‐catalyzed polymerization of 1,3‐diphenylyne–calix[4]arene compounds: Novel conjugated,calixarene‐based polymers

The synthesis of two 1,3‐bis(4‐ethynylbenzyloxy)calix[4]arenes, 5,11,17,23‐tetrakis(1,1‐dimethylethyl)‐25,27‐bis(4‐ethynylbenzyloxy)‐26,28‐dihydroxycalix[4]arene ( 1 ) and 25,27‐bis(4‐ethynylbenzyloxy)‐26,28‐dihydroxycalix[4]arene ( 2 ), was accomplished through Sonogashira coupling of appropriate calixarene derivatives. Methods for the polymerization of these bifunctional building blocks with Rh(I) as a catalyst, leading ultimately to conjugated polymers having calix[4]arene units incorporated into the main chain, were explored. Calixarenes 1 and 2 were efficiently polymerized with rhodium‐based initiators and afforded the conjugated polymers poly{5,11,17,23‐tetrakis(1,1‐dimethylethyl)‐25,27‐bis(4‐ethynylbenzyloxy)‐26,28‐dihydroxycalix[4]arene} ( poly 1 ) and poly{25,27‐bis(4‐ethynylbenzyloxy)‐26,28‐dihydroxycalix[4]arene}. Depending on the conditions, high conversions and good yields were obtained. The effects of adding cocatalysts (NHEt₂ and/or PPh₃) were studied in connection with the number‐average molecular weight and the molecular weight distribution of the resultant polymer ( poly 1 ) and tentatively correlated with the formation of low‐molecular‐weight materials. A catalytic system containing triphenylphosphine as the sole additive ([Rh(nbd)Cl]₂; [Rh]/[PPh₃] = 0.5) proved to be the best for the polymerization of p‐tert‐butylcalixarene compound 1 . Linear polymers having high number‐average molecular weights (up to 1.1 × 10⁵ g mol^?1) with low polydispersities were produced under these conditions. For debutylated homologue 2 , its polymerization was best carried out in the absence of any added cocatalyst. A cyclopolymerization route, comprising the intramolecular ring closing of the calix[4]arene pendant ethynyl groups followed by an intermolecular propagation step, is advanced to explain the results. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 7054–7070, 2006     

Modeling the framework stability and catalytic activity of pure and transition metal-doped zeotypes

We present a thorough computational study of transition metal-doped zeolite and aluminophosphate (AlPO) frameworks. The structural and electronic chemistry of the dopants is examined with ab initio quantum mechanical calculations, and the results correlated with the Brønsted and Lewis acid strength, and with the redox potential of the dopant ions in the framework. The energetics of doping is provided, and is employed to analyze the mode of dopant incorporation, and its site ordering in the microporous framework. In total, 23 dopant ions are examined in the isostructural framework of chabasite and AlPO-34. These cover most of the isomorphous framework replacements known to occur experimentally, but also framework replacements that have not yet been achieved. In this case, ab initio modeling techniques are employed in a predictive way. Finally, we present a computational study of the alkene epoxidation on titanosilicates, that covers the whole catalytic cycle.     

Creating Employment Opportunities for People with Mental Health Problems: A Feasibility Study for New Initiatives

This paper describes a feasibility study for the development of a network of employment services for people with mental health problems (and others) who are unemployed. It highlights the problems of using debate-orientated, soft OR methods when there are difficulties of open communication between different interest groups. In this case, the interest groups were clients and professionals in the mental health system. To bypass these difficulties, a series of confidential interviews was conducted with stakeholders. The issue of who was to be interviewed was resolved through a rolling programme of recommendations, where each interviewee recommended others until most of the people being recommended were people who had already been seen. This approach allowed for the involvement of many people and agencies who the researchers did not initially suspect might be stakeholders. Having conducted the interviews, the researchers then produced a design in the form of an ‘expert’ report. Although they had serious reservations about taking such an approach instead of simply supporting the expertise of already identified stakeholders, it turned out, upon reflection, that they had made the right decision. The ‘expert’ appoach allowed the views of service users to be taken into account. Also, the rolling programme of recommendations used to determine who should be interviewed actually uncovered hitherto ‘hidden’ stakeholders who were crucial to the success or failure of the whole project.     

Separation and Turbulence Control in Biomimetic Flows

The study of the flow around live marine animals and robotic mechanisms which emulate fish motion has revealed a number of mechanisms of flow control, optimised through evolution to minimize the energy required for steady and unsteady motion underwater. We outline some of the mechanisms used to (a) eliminate separation, (b) reduce turbulence, and (c) extract energy from oncoming vortical flows.     

Application of the copper catalysed N-arylation of amidines in the synthesis of analogues of the chemical tool, blebbistatin

A robust protocol for the CuI-catalysed arylation of amidines is presented. Whilst the initially identified conditions were useful for benzamidine-derived substrates, difficulties were encountered with more complex substrates. This problem was overcome following a change in ligand type, enabling the synthesis of analogues of the chemical tool, blebbistatin.