Wavelength-Selective Caged Surfaces: How Many Functional Levels Are Possible?

Abstract

The possibility of wavelength-selective cleavage of seven photolabile caging groups from different families has been studied. Amine-, thiol-, and carboxylic-terminated organosilanes were caged with o-nitrobenzyl (NVOC, NPPOC), benzoin (BNZ), (coumarin-4-yl)methyl (DEACM), 7-nitroindoline (DNI, BNI), and p-hydroxyphenacyl (pHP) derivatives. Caged surfaces modified with the different chromophores were prepared, and their photosensitivity at selected wavelengths was quantified. Different pairs, trios, and quartets of chromophore combinations with wavelength-selective photoresponse were identified. Our results show, for the first time, the possibility of generating surfaces with up to four different and independently addressable functional levels. In addition, this manuscript presents the first systematic comparison of the photolytic properties of different photolabile groups under different irradiation conditions.

Multiphoton Reactive Surfaces Using Ruthenium(II) Photocleavable Cages

“…12,16 In this equation x represents the relative surface coverage of the photoreactive group and I 0 is the illumination intensity in einstein per units of time and area.…”

“…More recently 2-nitrobenzyl, 7-nitroindoline, coumarin-4-ylmethyl, p-hydroxyphenacyl, or benzoin caged surfaces were also reported. 12 All of them show their optimum photoactivity in the UV spectral range, but uncaging fails or it becomes inefficient in the visible range. This fact constitutes an important limitation of caged surfaces in applications involving biological species.…”

Photochemical electrocyclic ring closure and leaving group expulsion from N-(9-oxothioxanthenyl)benzothiophene carboxamides

“…It should be noted that the above wavelength maxima do not represent the practical, usually longer wavelengths used for photorelease experiments. 23 In addition, certain cage compounds, including 35 coumarinylmethyl 20 and hydroxyquinolinylmethyl 21 derivatives undergo uncaging upon 2-photon excitation in the IR region. 24 Four aspects of the photochemistry of 7-9 and 10 will be discussed further, below.…”

“…After hot vacuum filtration through silica gel, the silica gel was washed with 30 mL and combined with the filtrate. The Preparation of N-(7-bromo-9-oxo-9H-thioxanthen-2-yl)-acetamide (23). A mixture of 1.0 g (3.3 mmol) amino ketone 21, 50 mL glacial acetic acid, and 11.6 g (114 mmol) of acetic 110 anhydride was stirred for overnight at room temperature.…”

Diffusion-controlled sensitization of photocleavage reactions on surfaces

“…[1][2][3] Apart from DNA chips, the fabrication of microarrays of other biomolecules at surfaces has also been reported. [4][5][6][7] In a recent paper by San Miguel et al, 8 the photodeprotection of caged surfaces was investigated with seven different photocleavable groups and their photosensitivity at different wavelengths were quantified, and wavelength selectivity was demonstrated. Besides others, the o-nitrobenzyl (oNB) group and its derivatives have figured most prominently as photoremovable protecting groups in the photolithographic synthesis of oligonucleotide arrays.…”