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Lectures & Events

Thursday 30 May
Perlman Chemical Sciences Building 10:00
Chemical and Biological Physics Guest Seminar Dr. Alexandre Kabla [Info]

Chemical and Biological Physics Guest Seminar

Cell migration and cell mechanics play a crucial role in a number of key biological processes, such as embryo development or cancer metastasis. Understanding the way cells control their own material properties and mechanically interact with their environment is key. At a more fundamental level, there is need better measure, describe and monitor cell and tissue mechanics before we can formulate testable hypotheses. In this talk, I will report experimental studies on the mechanical response of two different multicellular structures: epithelial monolayers and early embryonic tissues. In both cases, the material exhibits a strong time-dependent response over a broad distribution of time-scales. The combination of mechanical characterisation with biological perturbations offers new insight into the mechanisms exploited by cells and tissue to control their mechanical properties. This insight is however limited by the lack of consistency in experimental protocols and modelling strategies used in the field. We recently developed a systematic approach to capture material properties from mechanical behaviours and made progress assessing the model’s generality over a broad range of biological systems University of Cambridge. UK
Tuesday 04 June
Helen and Milton A. Kimmelman Building 11:00
Phosphorus-Element Bond-Forming Reactions Prof. Christopher C. Cummins [Info]

Phosphorus-Element Bond-Forming Reactions

Reactive Intermediates & Group Transfer Reactions. We design and synthesize molecular precursors that can be activated by a stimulus to release a small molecule of interest. The molecular precursors themselves are isolated as crystalline solids; they are typically soluble in common organic solvents and can be weighed out and used as needed. For example, the molecule P2A2 (A = anthracene or C14H10) is a molecular precursor to the diatomic molecule P2. Compounds having the formula RPA serve to transfer the phosphinidene (PR) group either as a freely diffusing species (R = NR’2, singlet phosphinidene) or else by inner sphere mechanisms (R = alkyl, triplet phosphinidene). Using the RPA reagents we are developing reactions analogous to cyclopropanation and aziridination for delivery of the PR group to olefins with the formation of three-membered P-containing rings, phosphiranes. Metaphosphates and Phosphorylating Methodology. Crystalline metaphosphate salts with lipophilic counter cations are useful starting materials applicable in polar organic media. “Metaphosphate” refers to the inorganic ion PO3(-) which, unlike its chemical cousin, nitrate, exists not as a monomeric species but rather as oligomeric rings: [(PO3)n]n-. These cyclic phosphates can be converted into electrophilic phosphorylating agents (a) by treatment with peptide coupling reagents, or (b) by conversion into their crystalline acid forms and subsequent dehydration. Such activated cyclic phosphates can be used directly for oligophosphorylation of C, N, and O nucleophiles. Phosphorylation of the Wittig reagent leads to a new phosphorus ylide with a cyclic phosphate as the C-substituent and a non-hydrolyzable P-C bond, allowing for conjugation of oligophosphate groups to a biomolecule of interest by aldehyde olefination. Sustainable Phosphorus Chemistry. The industrial “thermal process” by which the raw material phosphate rock is upgraded to white phosphorus is energy intensive and generates CO2. We seek alternative chemical routes to value-added P-chemicals from phosphate starting materials obtained either by the agricultural “wet process” or by phosphorus recovery and recycling from waste streams. Trichlorosilane is a high production volume chemical for its use in the manufacture of silicon for solar panels. We show that trichlorosilane is a reductant for phosphate raw materials leading to the bis(trichlorosilyl) phosphide anion [P(SiCl3)2]- as a versatile intermediate en route to compounds containing P-C bonds. Department of Chemistry, MIT
Thursday 13 June
Perlman Chemical Sciences Building 02:00
Chemical and Biological Physics Dept Seminar Prof. Phil Pincus [Info]

Chemical and Biological Physics Dept Seminar

University of California, Santa Barbara