Thomas A. Logothetis

Crystal engineering of brominated tectons: N-methyl-3,5-dibromo-pyridinium iodide gives particularly short C–Br⋯I halogen bonding

The crystal matrix of N-methyl-3,5-dibromopyridinium iodide is constituted of infinite helices where the cation and the anion alternate and are bound by the second shortest reported C–Br⋯I halogen bonding. The electron poor pyridinium scaffold is particularly effective in boosting the electron acceptor ability of bromine substituents.

2-C-TRIFLUOROMETHYL SUBSTITUTED PENTOSES

The synthesis of racemic 2-C-trifluoromethyl ribose and racemic 2-C-trifluoromethyl arabinose is described. The four step reaction sequence includes diastereoselective enol ether addition to methyl trifluoropyruvate, diastereoselective dihydroxylation of the CC double bond with potassium osmate, lactonization, and finally SMEAH reduction to give the lactol. 2-C-Trifluoromethyl pentoses exhibit unexpected anomeric and tautomeric stabilities.

2-C-trifluoromethyl substituted 3-deoxypentoses

An efficient synthesis of 2-C-trifluoromethyl substituted 3-deoxypentoses starting from trifluoropyruvates is described.

A Resin-linker-vector approach to radiopharmaceuticals containing 18F: application in the synthesis of O-(2-[18F]-Fluoroethyl)-L-tyrosine

A Resin-linker-vector (RLV) strategy is described for the radiosynthesis of tracer molecules containing the radionuclide (18)F, which releases the labelled vector into solution upon nucleophilic substitution of a polystyrene-bound arylsulfonate linker with [(18)F]-fluoride ion. Three model linker-vector molecules 7a-c containing different alkyl spacer groups were assembled in solution from (4-chlorosulfonylphenyl)alkanoate esters, exploiting a lipase-catalysed chemoselective carboxylic ester hydrolysis in the presence of the sulfonate ester as a key step. The linker-vector systems were attached to aminomethyl polystyrene resin through amide bond formation to give RLVs 8a-c with acetate, butyrate and hexanoate spacers, which were characterised by using magic-angle spinning (MAS) NMR spectroscopy. On fluoridolysis, the RLVs 8a,b containing the longer spacers were shown to be more effective in the release of the fluorinated model vector (4-fluorobutyl)phenylcarbamic acid tert-butyl ester (9) in NMR kinetic studies and gave superior radiochemical yields (RCY≈60%) of the (18) F-labelled vector. The approach was applied to the synthesis of the radiopharmaceutical O-(2-[(18)F]-fluoroethyl)-L-tyrosine ([(18) F]-FET), delivering protected [(18) F]-FET in >90% RCY. Acid deprotection gave [(18)F]-FET in an overall RCY of 41% from the RLV.

Effects of using structured templates for recalling chemistry experiments

AbstractBackgroundThe way that we recall information is dependent upon both the knowledge in our memories and the conditions under which we recall the information. Electronic Laboratory Notebooks can provide a structured interface for the capture of experiment records through the use of forms and templates. These templates can be useful by providing cues to help researchers to remember to record particular aspects of their experiment, but they may also constrain the information that is recorded by encouraging them to record only what is asked for. It is therefore unknown whether using structured templates for capturing experiment records will have positive or negative effects on the quality and usefulness of the records for assessment and future use. In this paper we report on the results of a set of studies investigating the effects of different template designs on the recording of experiments by undergraduate students and academic researchers.ResultsThe results indicate that using structured templates to write up experiments does make a significant difference to the information that is recalled and recorded. These differences have both positive and negative effects, with templates prompting the capture of specific information that is otherwise forgotten, but also apparently losing some of the personal elements of the experiment experience such as observations and explanations. Other unexpected effects were seen with templates that can change the information that is captured, but also interfere with the way an experiment is conducted.ConclusionsOur results showed that using structured templates can improve the completeness of the experiment context information captured but can also cause a loss of personal elements of the experiment experience when compared with allowing the researcher to structure their own record. The results suggest that interfaces for recording information about chemistry experiments, whether paper-based questionnaires or templates in Electronic Laboratory Notebooks, can be an effective way to improve the quality of experiment write-ups, but that care needs to be taken to ensure that the correct cues are provided.Graphical abstractScientists have traditionally recorded their research in paper notebooks, a format that provides great flexibility for capturing information. In contrast, Electronic Laboratory Notebooks frequently make use of forms or structured templates for capturing experiment records. Structured templates can provide cues that can improve record quality by increasing the amount of information captured and encouraging consistency. However, using the wrong cues can lead to a loss of personal elements of the experiment experience and frustrate users. This image shows two participants from one of our studies recording their experiment using a computer-based template