Albert M Brouwer

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In previous studies, subjects did not hit slowly moving objects as quickly as fast ones, despite being instructed to hit them all as quickly as possible. In those studies the targets moved at constant but unpredictable velocities, and it has been suggested that subjects were unable to adjust the hand's path to suit the velocity of the target. To compensate(More)
The photocycle of the photoactive yellow protein (PYP) from Ectothiorhodospira halophila was examined by time-resolved difference absorption spectroscopy in the wavelength range of 300-600 nm. Both time-gated spectra and single wavelength traces were measured. Global analysis of the data established that in the time domain between 5 ns and 2 s only two(More)
The photoisomerization of the push-pull substituted azo dye Disperse Red 1 is studied using femtosecond time-resolved absorption spectroscopy and other spectroscopic and computational techniques. In comparison with azobenzene, the pipi* state is more stabilized by the effects of push-pull substitution than the npi* state, but the latter is probably still(More)
Control of the shuttling process in rotaxanes using external sources has been the subject of considerable recent research.1 Photoinduced motions are particularly interesting because of the convenient use of this stimulus in possible future device applications. Up to now, however, translational shuttling in photoactive rotaxanes has required external(More)
Establishing methods for controlling aspects of large amplitude submolecular movements is a prerequisite for the development of artificial devices that function through rotary motion at the molecular level. Here we demonstrate that the rate of rotation of the interlocked components of fumaramide-derived [2]rotaxanes can be accelerated, by >6 orders of(More)
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)
A series of molecular motors featuring a symmetrical acridane stator is reported. Photochemical and thermal isomerization experiments confirm that this stator, in combination with a thiopyran rotor, results in molecular rotary motion in which the rate-determining thermal helix inversion proceeds effectively only at temperatures above 373 K. The introduction(More)
Azobenzene functionalized with ortho-fluorine atoms has a lower energy of the n-orbital of the Z-isomer, resulting in a separation of the E and Z isomers' n→π* absorption bands. Introducing para-substituents allows for further tuning of the absorption spectra of o-fluoroazobenzenes. In particular, electron-withdrawing ester groups give rise to a 50 nm(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 solvatochromic behavior of N-(2,5-di-tert-butylphenyl)-9-pyrrolidinoperylene-3,4-dicarboximide () was investigated by measuring the excitation and emission spectra over a wide range of temperature in 2-methyltetrahydrofuran (MTHF). The temperature induced spectral changes can be compared with the changes caused by changing solvent polarity using(More)