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DTSTART;TZID=America/Los_Angeles:20230403T150000
DTEND;TZID=America/Los_Angeles:20230403T160000
DTSTAMP:20260613T214407
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UID:28706-1680534000-1680537600@www.chemistry.ucla.edu
SUMMARY:Houk-Jung Organic Colloquium 247: Daniel T. Gryko
DESCRIPTION:1\,4-Dihydropyrrolo[3\,2-b]pyrrole and Dipyrrolonaphthyridinedione – Novel Building Blocks for Optoelectronics \nAbstract: Recently we have discovered and optimized the first practical synthesis of non-fused pyrrole[3\,2-b]pyrroles via domino reaction of aldehydes\, primary amines\, and butane-2\,3-dione.1 Six bonds are formed in heretofore unknown tandem process\, which gives rise to substituted pyrrole[3\,2-b]pyrroles – the ‘missing link’ on the map of aromatic heterocycles. Unparalleled simplicity and versatility of this one-pot reaction\, non-chromatographic purification and superb optical properties (including strong violet\, blue or green fluorescence both in solution as well as in the solid state)\, brought these molecules from virtual non-existence to the intensively investigated area functional π-systems. The parent 1\,4-dihydro-pyrrolo[3\,2-b]pyrroles served as building block to construct various π-expanded analogs including nitrogen-embedded buckybowl with inverse Stone–Thrower–Wales topology2\,3 and diindolo[2\,3-b:2‘\,3‘–f]pyrrolo[3\,2-b]pyrroles. These compounds constitute the most electron-rich ladder-type heteroacenes known to date – EHOMO was located at ca. −4.6 eV. Recently\, we have proved that the dipyrrolonaphthyridinedione (DPND) core constitutes an excellent scaffold for the design of strongly fluorescent dyes or quadrupolar-type materials with large two-photon absorption (TPA) cross-sections (up to 5\,180 GM).37 These properties result from an unusual arrangement of donor (pyrrole ring) and acceptor (carbonyl group) moieties within the DPND core.
URL:https://www.chemistry.ucla.edu/events/houk-jung-organic-colloquium-247-daniel-t-gryko/
LOCATION:Mol Sci 3440\, 607 Charles E. Young Dr.\, East\, Los Angeles\, CA\, 90095\, United States
CATEGORIES:Organic Colloquium
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DTSTART;TZID=America/Los_Angeles:20230403T160000
DTEND;TZID=America/Los_Angeles:20230403T170000
DTSTAMP:20260613T214407
CREATED:20230310T172703Z
LAST-MODIFIED:20230310T172703Z
UID:28553-1680537600-1680541200@www.chemistry.ucla.edu
SUMMARY:Physical Chemistry Seminar 228: Dugan Hayes
DESCRIPTION:Hayes Flyer \nTime-resolved Spectroscopic Tools for Mechanistic Studies of Organic and Inorganic Photochemistry \nAbstract: Ultrafast optical spectroscopies are powerful tools for characterizing electronic excited state dynamics in homogeneous photochemistry. When the system of interest contains a transition metal\, we may also take advantage of the element specificity of X-ray spectroscopies to provide complementary information. I will provide two examples of recent work from my group that take advantage of the powerful combination of these techniques to disentangle photochemical and photophysical pathways. First\, I will present our investigation of the Cu(I)-catalyzed [2 + 2] photocycloaddition reaction\, which provides a simple\, single-step route to cyclobutanes in organic syntheses. By observing the intermolecular dimerizations of two model olefins\, we have found that this photocatalytic reaction may be directed along strikingly disparate trajectories through only very minor changes in substrate structure. These insights have since allowed us to overcome the limitations of intramolecular [2 + 2] photocyloadditions and thereby broaden the scope of such reactions. Next\, I will present our work on the aqueous ferrate(VI) ion\, a remarkable example of an air-stable hexavalent iron complex that is an excellent source of oxidizing potential in both catalysis and energy storage applications. We have identified the timescales\, intermediates\, and branching ratios for the competing photochemical and photophysical relaxation pathways of the ferrate(VI) ligand-to-metal charge transfer state\, which will help guide environmental engineering efforts toward novel\, non-toxic methods of oxidative water treatment. Finally\, I will discuss how we have used organic chromophores as platforms for the discovery of novel photochemical reactions with unique regioselectivity and give several examples of such transformations.
URL:https://www.chemistry.ucla.edu/events/physical-chemistry-seminar-228-dugan-hayes/
LOCATION:Mani L. Bhaumik Centennial Collaboratory\, 607 Charles E. Young Dr.\, East\, Los Angeles\, CA\, 90095\, United States
CATEGORIES:Physical Chemistry Seminar
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