Albert M Brouwer

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A rotaxane is described in which a macrocycle moves reversibly between two hydrogen-bonding stations after a nanosecond laser pulse. Observation of transient changes in the optical absorption spectrum after photoexcitation allows direct quantitative monitoring of the submolecular translational process. The rate of shuttling was determined and the influence(More)
Rotaxanes comprise macrocycles that can shuttle between docking stations along an axle. We explored the nanosecond shuttling mechanism by reversing the relative binding affinities of two stations through ultraviolet-induced transient reduction. We monitored the ensuing changes in the CO-stretching bands of the two stations and the shuttling macrocycle by(More)
The area of contact between two objects was detected by using the strong enhancement of the fluorescence of rigidochromic probe molecules attached to one of the surfaces. Confinement of the molecules suppresses nonradiative decay and turns on the fluorescence. The approach is demonstrated by imaging of the contact area of a plastic sphere in contact with a(More)
Two fluorescent derivatives of 2-amino-3-carbonitrile-4H-chromene were synthesized by means of a fluorogenic Michael addition of dimedone to dicyano alkene labeled BODIPY derivatives. Different organocatalysts were used in different conditions to obtain compounds 3 and 4 in good yield (up to 65% and 85%) and moderate enantiomeric excess (51% and 41% ee,(More)
A series of new benzo[ghi]perylenetriimide (BPTI) derivatives has been synthesized and characterized. These remarkably soluble BPTI derivatives show strong optical absorption in the range of λ=300-500 nm and have a high triplet-state energy of 1.67 eV. A cyanophenyl substituent renders BPTI such a strong electron acceptor (Ered =-0.11 V vs. the normal(More)
Repartitioning of co-solvents between particles of latex emulsions was investigated by means of a fluorescence method based on the detection of the amount of co-solvent via the solvatochromic shift of the emission maximum of a fluorescent probe, copolymerized at a low concentration. Complete repartitioning of co-solvents between particles of latex materials(More)
Two classes of rotaxanes are described in which photoinduced processes modulate a large-amplitude motion. In the first type, E–Z-isomerization of a fumaric diamide unit to a maleic diamide leads to a substantial weakening of the hydrogen bonds between the diamide and the macrocyclic ring that surrounds it. As a result, the rate of the pirouetting motion is(More)
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