Optical Switching and Antenna Effect of Dendrimers with an Anthracene Core

Abstract

Dendrimers 6G(i) (i=1-4) consisting of an anthracene core and Fréchet dendrons which are attached via a CH(2)OCH(2) chain in the 9-position undergo quantitative and completely reversible intramolecular [4pi+4pi] cycloaddition. The process can be monitored by absorption and fluorescence measurements. The Fréchet dendrons act as an energy funnel that collects and focuses the photon energy but does not change the photostationary states, which for both directions are completely on the product side when the separate chromophores are selectively irradiated. The quantum yields of anthracene fluorescence and of singlet energy transfer from the dendrons to the core were studied as a function of dendrimer generation.

Effect of solvent-controlled aggregation on the intrinsic emission properties of PAMAM dendrimers

“…Recent research focuses more on effective ways of tuning the properties of dendrimers for practical applications [10,11]. Modification in structure, size and shape of the dendritic design provides an attractive pathway for controlling the properties of dendrimers [2,[12][13][14]. While dendrimers possess unambiguous structural features compared to polymers due to differences in morphological architecture, external factors such as pH [15,16], concentration [17] and solvation [18][19][20] can bring considerable structural flexibility to dendrimers.…”

Synthesis of Fréchet-type dendritic homotriptycenes

“…Photoacids, which replace the second wedge in 10-position of the anthracene core, should enable the triggering of the process by light, whereby the antenna effect of the Fréchet dendrons [43] can be extremely useful.…”

Optical switches with biplanemers obtained by intramolecular photocycloaddition reactions of tethered arenes

“…In previous years many publications on applications of the reversible reaction 1 $ 2 in supramolecular chemistry and materials science appeared. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] In principle, such a switch can be monitored by any (physical) property which is sufficiently different for 1 and 2. An easy control is possible by measuring the absorbance of 1 and 2 at a certain excitation wavelength.…”

“…2 visualizes intramolecular excimers/exciplexes E*, pericyclic minima PM* for a concerted reaction and diradicals DR, which may have zwitterionic character. 2,3,14 Normally, the switching processes 1 $ 2 are performed in solution; however, many topochemically controlled reactions in the solid state are known as well.…”