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X-WR-CALDESC:Events for UCLA
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DTSTART:20220313T100000
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DTSTART;TZID=America/Los_Angeles:20220210T120000
DTEND;TZID=America/Los_Angeles:20220210T120000
DTSTAMP:20260615T012838
CREATED:20220121T010646Z
LAST-MODIFIED:20220121T010646Z
UID:13596-1644494400-1644494400@www.chemistry.ucla.edu
SUMMARY:James Gaynor\, Postdoc Fellow\, University of California\, Berkeley Seminar
DESCRIPTION:Stories of Coherence: From Vibronic to Electronic Phenomena \nA robust understanding of chemical reactivity in excited states is essential for designing and discovering new ways of harnessing energy flow at the atomic and molecular level. Photo-induced coherent processes\, which utilize atomic or molecular motions moving with a well-defined phase relationship\, may enhance control over important photochemical events. This presentation explores a wide range of timescales over which coherence and decoherence occur in solution phase molecules\, gas phase atoms\, and in “atomic-like” excitations of a crystalline ionic solid. We will begin with a new perspective on the first two picoseconds of excited state charge transfer involving coupled electronic and vibrational (i.e.\, “vibronic”) motions in solution phase solar cell dye molecules. Next\, pure electronic coherences in a noble gas are investigated in the absence of vibrational or environmental perturbations\, lasting for hundreds of femtoseconds. Finally\, we return to the condensed phase in the solid form\, where many-body electron correlations appear to cause core-excited state dephasing on sub-10 femtosecond timescales.
URL:https://www.chemistry.ucla.edu/seminars/james-gaynor-postdoc-fellow-university-california-berkeley-seminar/
CATEGORIES:Physical Chemistry Seminar,Seminars
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BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20220210T160000
DTEND;TZID=America/Los_Angeles:20220210T160000
DTSTAMP:20260615T012838
CREATED:20210816T221714Z
LAST-MODIFIED:20210816T221714Z
UID:13533-1644508800-1644508800@www.chemistry.ucla.edu
SUMMARY:Battery-Inspired Strategies for Electrocatalytic C–C and C–N Bond-Forming Reactions
DESCRIPTION:Abstract: The seminar will describe our efforts towards the development of scalable\, mild\, and general electrosynthetic methodologies for C–C and C–N/X coupling reactions. These electrosynthetic methodologies are largely possible because of a synergy between redox-active mediators developed by the energy storage community and transition metal catalysts. It will be shown that yields from electrocatalytic reactions are greatly improved by the incorporation of co-catalytic quantities of soluble battery compounds that mediate electron transfer with the coupling catalyst or protect the coupling catalyst from over-oxidation/reduction and degradation. \nEmploying mediators with properly tuned redox potentials and electron-transfer kinetics\, we demonstrate electrocatalytic cross-electrophile coupling reactions of (hetero) aryl halides and alkyl halides that represent the state of the art in the area. Additionally\, we demonstrate a broad scope for Chan-Lam coupling of amines and arylboronic acids in the absence of a chemical oxidants. Our studies reveal unique mechanisms that are only accessible under electrochemical conditions that enable cross coupling of tertiary electrophiles or arylchlorides: challenging substrates that are currently incompatible with any form of reductive activation.
URL:https://www.chemistry.ucla.edu/seminars/tba-14/
CATEGORIES:Organic Colloquium,Seminars
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