Use of metal catalysts bearing Schiff base macrocycles for the ring opening polymerization (ROP) of cyclic esters

© 2017 by the authors. Schiff base macrocycles are emerging as useful scaffolds for binding two or more catalytic metals in close proximity. Such coordination chemistry allows for the evaluation of potentially beneficial catalytic cooperative effects. In the field of ring opening polymerization (ROP) of cyclic esters, only a handful of metal systems bound by Schiff base [2 + 2] type macrocycles have been studied. Nevertheless, results to date have, for certain metals, identified some interesting structure activity relationships, whilst for other systems results have revealed particular combinations of metals and macrocycles to be virtually inactive. This perspective review takes a look at two types of recently-reported Schiff base macrocycles that have been employed as pro-ligands in the metal-catalyzed ROP of cyclic esters, specifically ε-caprolactone and rac-lactide

Molecular catalysis for precise olefin polymerization and ROP 2015

The growth of emerging markets, particularly in the Far East, has fuelled the demand for new plastic materials. This in turn has stimulated both academic and industrial interest in the design of catalyst systems for which new Intellectual Property (IP) can be generated, and in new polymeric materials possessing desirable properties such as biodegradabilit

Metallocalixarene catalysts: α-olefin polymerization and ROP of cyclic esters

This perspective review discusses metallocalix[n]arene complexes that have been employed in either α-olefin polymerization or in the ring opening polymerization (ROP) of cyclic esters over the last 5 years. Synthesis, molecular structure and catalytic potential are discussed. For α-olefin polymerization, systems based on early transition metals in combination with calix[n]arenes (n = 4, 6 or 8), depleted calix[4]arenes or thia/sulfinyl/sulfonyl calix[4]arenes have been reported, and in some cases, are highly active. For the ROP studies, a number of the systems, typically of the early transition metals, only exhibit activity under robust conditions, whereas other systems, for example those of magnesium, demonstrate exceptional activity, immortal behaviour and intriguing stereoselectivity

Direct evidence of a blocking heavy atom effect on the water-assisted fluorescence enhancement detection of Hg²⁺ based on a ratiometric chemosensor

At the current stage of chemosensor chemistry, the critical question now is whether the heavy atom effect caused by HTM ions can be blocked or avoided. In the present work, we provide unequivocal evidence to confirm that the heavy atom effect of Hg²⁺ is inhibited by water and other solvent molecules based on results using the chemosensor L. Most importantly, the heavy atom effect and blocking thereof were monitored within the same system by the use of ratiometric fluorescence signal changes of the pyrene motif. These observations not only serve as the foundation for the design of new ‘turn-on’ chemosensors for HTM ions, but also open up new opportunities for the monitoring of organic reactions

Driving Cultures: Cars, Young People and Cultural Research

This article describes the Driving Cultures research, the cultural importance of the car and the psychological approaches central to research in the field of road safety and investigations of the over–representation of young people in crashes. The aim of the article is to outline driving as a cultural practice drawing on the experiences of young people as described in focus groups in order to show how cultural research can contribute to a social concern such as traffic injury and death

What is digital society? Reflections on the aims and purpose of digital sociology

Joint book revie

Walking from the Car

A review of Mike Featherstone, Nigel Thrift, and John Urry (eds), Automobilities (Sage, London, 2005)

Dichloropalladium complexes ligated by 4,5-bis(arylimino)pyrenylidenes: Synthesis, characterization, and catalytic behavior towards Heck-reaction

A series of 4,5-bis(arylimino)pyrenylidenylpalladium(II) chloride complexes (C1–C4) were synthesized and characterized by FT-IR and NMR spectroscopy, elemental analysis as well as by single crystal X-ray diffraction for the representative complexes C1 and C3, which revealed a square planar geometry at the palladium center. All palladium complexes exhibited high activity for the Heck cross-coupling reaction, which were effective when conducted in various solvents. Furthermore, the in-situ mixture of palladium dichloride and the ligand (L1) provided an effective catalytic system for the Heck-reaction

Dialkylaluminium 2-imidazolylphenolates: Synthesis, characterization and ring-opening polymerization behavior towards lactides

The stoichiometric reaction of the 2-imidazolylphenols (L1–L9) with the trialkylaluminium reagents AlR₃ (R = Me, Et and iBu), afforded the corresponding dialkylaluminium 2-imidazolylphenolate complexes [R₂Al(L1–L9)] (C1–C11), which were characterized by ¹H/¹³C NMR spectroscopy and by elemental analysis. The molecular structures of the representative complexes C1, C2, C4, C6 and C11 were determined by single-crystal X-Ray diffraction, and revealed a distorted tetrahedral geometry at aluminum. These dialkylaluminium 2-imidazolylphenolates (C1–C11) could efficiently catalyze the ring-opening polymerization of lactides to afford high molecular weight polylactide, both in the presence and absence of BnOH, and as such represent rare examples of the use of bi-dentate ligation at aluminum in such lactide polymerization systems. On the basis of the polymerization results for l-lactide, d-lactide and rac-lactide, the nature of the ligands and the aluminum bound alkyls were found to significantly affect the catalytic activity as well as the properties of the resultant polylactides

Delivered With Care. A National Survey of Women's Experience of Maternity Care 2010

As maternity services change and the population of women and families served also changes, there is a need to document the views of women with recent experience of care. Maternity services are evolving and the information from this study provides a picture of current practice and point of comparison for the future. This survey was carried out in 2010 and used similar methods to those employed in 1995 and 2006. A random sample of 10,000 women giving birth in England over a two week period were selected by the Office for National Statistics from birth registration records. Women whose babies had died and new mothers less than 16 years of age were excluded. The usable response rate was 54%, with 5,333 women participating. A total of 14% of respondents came from Black and Minority Ethnic (BME) groups and 21% had been born outside the UK. An online version of the questionnaire was made available to all survey participants; only 8% of those responding used this method of return. Data were analysed and are presented by parity, with some specific univariate analyses in relation to clinical factors such as mode of delivery and demographic factors, such as maternal age or geographical region. Some comparisons are made with previous surveys. Multivariate analyses, with adjustment for potential confounders, were carried out in relation to 20 selected outcomes contributing to quality of care