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1.
J Am Chem Soc ; 142(52): 21651-21655, 2020 12 30.
Artigo em Inglês | MEDLINE | ID: mdl-33337866

RESUMO

Herein, we introduce a comprehensive methodology to map the reactivity of photochemical systems on surfaces. The reactivity of photoreactive groups in solution often departs from their corresponding solution absorption spectra. On surfaces, the relationship between the surface absorption spectra and reactivity remains unexplored. Thus, herein, the reactivity of an o-methylbenzaldehyde and a tetrazole, as ligation partners for maleimide functionalized polymers, was investigated when the reactive moieties are tethered to a surface. The ligation reaction of tetrazole functionalized surfaces was found to proceed rapidly leading to high grafting densities, while o-methylbenzaldehyde functionalized substrates required longer irradiation times and resulted in lower surface coverage at the same wavelength (330 nm). Critically, wavelength resolved reactivity profiles were found to closely match the surface absorption spectra, contrary to previously reported red shifts in solution for the same chromophores.

2.
Chemistry ; 26(71): 16985-16989, 2020 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-32839970

RESUMO

We report a photochemical reaction system which requires activation by two colors of light. Specifically, a dual wavelength gated system is established by fusing the visible light mediated deprotection of a dithioacetal with the UV light activated Diels-Alder reaction of an o-methylbenzaldehyde with N-ethylmaleimide. Critically, both light sources are required to achieve the Diels-Alder adduct, irradiation with visible or UV light alone does not lead to the target product. The introduced dual gated photochemical system is particularly interesting for application in light driven 3D printing, where two color wavelength activated photoresists may become reality.

3.
J Am Chem Soc ; 142(17): 7744-7748, 2020 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-32293171

RESUMO

We introduce a highly efficient photoligation system, affording a pro-fluorescent Diels-Alder product that, on demand, converts into an intensively fluorescent naphthalene via E1 elimination in the presence of catalytic amounts of acid. The Diels-Alder reaction of the photocaged diene (o-quinodimethane ether or thioether) with electron-deficient alkynes is induced by UV or visible light. In contrast to previously reported ligation techniques directly leading to fluorescent products, the fluorescence is turned on after the photoligation. Thus, the light absorption of the fluorophore does not undermine the photoligation via competitive absorption, and as a result, photobleaching or side reactions of the fluorophore are not observed. Critically, the gated generation of a fluorescent product allows for fluorometric determination of the conversion. We employ a simple synthesis strategy for heterobifunctional electron-deficient alkynes allowing for facile functionalization of payload molecules.

4.
J Am Chem Soc ; 141(42): 16605-16609, 2019 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-31592659

RESUMO

We introduce the hybrid copolymerization of two disparate monomer classes (vinyl monomers and ring-strained cyclic olefins) via living photopolymerization. The living character of the polymerization technique (metal-free photo-ROMP) is demonstrated by consecutive chain-extensions. Further, we propose a mechanism for the copolymerization and analyze the copolymer structure in detail by high-resolution mass spectrometry.

5.
Adv Mater ; 31(8): e1807288, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30614578

RESUMO

A platform technology for multimaterial photoresists that can be orthogonally cured by disparate colors of light is introduced. The resist's photochemistry is designed such that one wavelength selectively activates the crosslinking of one set of macromolecules, while a different wavelength initiates network formation of a different set of chains. Each wavelength is thus highly selective towards a specific photoligation reaction within the resist. Critically, the shorter wavelength does not induce ligation of the longer wavelength selective species within the same resist mixture, defined as "wavelength orthogonality." Uniquely, this dual-color addressable resist system allows generating spatially resolved soft matter materials by simply selecting the curing wavelength, thus constituting a wavelength-orthogonal multimaterial resist with applications ranging from coatings to 3D additive manufacturing of multimaterial architectures.

6.
ACS Macro Lett ; 7(12): 1443-1447, 2018 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-35651225

RESUMO

Modern soft ionization mass spectrometry provides chemical information on various polymers with unparalleled resolution and sensitivity. However, the interpretation of the resulting highly complex mass spectra is hampered by the sheer amount of contributing macromolecular species. For example, state-of-the-art reversible deactivation radical polymerization techniques, which are generally considered to be highly controlled, can still generate tens or even hundreds of species in a narrow mass window. Moreover, the multitude of species typically leads to partially overlapping isotopic patterns, further complicating the data evaluation. Herein, a rapid and powerful three-step methodical approach is introduced that enables the successful identification and quantification of the contributing species. The approach is subsequently implemented in "pyMacroMS", a high performance algorithm that allows for ultrafast processing of high resolution polymer mass spectra with varying complexities. The power of our algorithm is demonstrated on the example of a photochemical atom transfer radical polymerization (photoATRP) of three monomers, ultimately leading to 908 identified species. pyMacroMS is available free of charge under a GNU General Public License v3.0.

7.
J Mater Chem B ; 1(46): 6427-6433, 2013 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-32261341

RESUMO

In this contribution, we describe ways to introduce additional complexity and functionality to protein mediated capsule formation based on biomineralization in Pickering templated systems in order to enable possible post-mineralization modifications. Here the shell morphology is influenced by addition of ionic additives to the reaction system which significantly alters the surface structure. By changing the oil-phase (tetraethyl orthosilicate), even more complexity is introduced as well as reactive groups by adding (3-aminopropyl)trimethoxysilane to the oil phase. The incorporated amino-functionality is easily addressed via mild peptide coupling reaction.

8.
Chem Commun (Camb) ; 48(80): 9983-5, 2012 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-22950083

RESUMO

A rare anion-π complex between bromide and a neutral receptor is reported and related receptor systems are studied with a series of anions. The interaction is observed in the solid state and in solution, and further evidence for it is obtained by a computational study.


Assuntos
Ânions/química , Benzamidas/química , Brometos/química , Ligação de Hidrogênio , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Conformação Molecular
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