TY  - JOUR
A1  - Barak, Arvind
A1  - Dhiman, Nishant
A1  - Sturm, Floriane
A1  - Rauch, Florian
A1  - Lakshmanna, Yapamanu Adithya
A1  - Findlay, Karen S.
A1  - Beeby, Andrew
A1  - Marder, Todd B.
A1  - Umapathy, Siva
T1  - Excited‐State Intramolecular Charge‐Transfer Dynamics in 4‐Dimethylamino‐4′‐cyanodiphenylacetylene: An Ultrafast Raman Loss Spectroscopic Perspective
JF  - ChemPhotoChem
N2  - Photo‐initiated intramolecular charge transfer (ICT) processes play a pivotal role in the excited state reaction dynamics in donor‐bridge‐acceptor systems. The efficacy of such a process can be improved by modifying the extent of π‐conjugation, relative orientation/twists of the donor/acceptor entities and polarity of the environment. Herein, 4‐dimethylamino‐4′‐cyanodiphenylacetylene (DACN‐DPA), a typical donor‐π‐bridge‐acceptor system, was chosen to unravel the role of various internal coordinates that govern the extent of photo‐initiated ICT dynamics. Transient absorption (TA) spectra of DACN‐DPA in n‐hexane exhibit a lifetime of >2 ns indicating the formation of a triplet state while, in acetonitrile, a short time‐constant of ∼2 ps indicates the formation of charge transferred species. Ultrafast Raman loss spectroscopy (URLS) measurements show distinct temporal and spectral dynamics of Raman bands associated with C≡C and C=C stretching vibrations. The appearance of a new band at ∼1492 cm\(^{−1}\) in acetonitrile clearly indicates structural modification during the ultrafast ICT process. Furthermore, these observations are supported by TD‐DFT computations.
KW  - charge transfer
KW  - ultrafast Raman loss spectroscopy
KW  - 4-dimethylamino-4′-cyanodiphenylacetylene
KW  - transient absorption
KW  - TD-DFT
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-312280
VL  - 6
IS  - 12
ER  - 
TY  - JOUR
A1  - Foster, Jonathan A.
A1  - Edkins, Robert M.
A1  - Cameron, Gary J.
A1  - Colgin, Neil
A1  - Fucke, Katharina
A1  - Ridgeway, Sam
A1  - Crawford, Andrew G.
A1  - Marder, Todd B.
A1  - Beeby, Andrew
A1  - Cobb, Steven L.
A1  - Steed, Jonathan W.
T1  - Blending Gelators to Tune Gel Structure and Probe Anion-Induced Disassembly
JF  - Chemistry : A European Journal
N2  - Blending different low molecular weight gelators (LMWGs) provides a convenient route to tune the properties of a gel and incorporate functionalities such as fluorescence. Blending a series of gelators having a common bis-urea motif, and functionalised with different amino acid-derived end-groups and differing length alkylene spacers is reported. Fluorescent gelators incorporating 1- and 2-pyrenyl moieties provide a probe of the mixed systems alongside structural and morphological data from powder diffraction and electron microscopy. Characterisation of the individual gelators reveals that although the expected α-urea tape motif is preserved, there is considerable variation in the gelation properties, molecular packing, fibre morphology and rheological behaviour. Mixing of the gelators revealed examples in which: 1) the gels formed separate, orthogonal networks maintaining their own packing and morphology, 2) the gels blended together into a single network, either adopting the packing and morphology of one gelator, or 3) a new structure not seen for either of the gelators individually was created. The strong binding of the urea functionalities to anions was exploited as a means of breaking down the gel structure, and the use of fluorescent gel blends provides new insights into anion-mediated gel dissolution.
KW  - blend
KW  - co-gels
KW  - fluorescence
KW  - orthogonal self-assembly
KW  - supramolecular chemistry
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-121141
VL  - 20
ER  -