title: A tunable azine covalent organic framework platform for visible light-induced hydrogen generation.
abstract: Hydrogen evolution from photocatalytic reduction of water holds promise as a sustainable source of carbon-free energy. Covalent organic frameworks (COFs) present an interesting new class of photoactive materials, which combine three key features relevant to the photocatalytic process, namely crystallinity, porosity and tunability. Here we synthesize a series of water- and photostable 2D azine-linked COFs from hydrazine and triphenylarene aldehydes with varying number of nitrogen atoms. The electronic and steric variations in the precursors are transferred to the resulting frameworks, thus leading to a progressively enhanced light-induced hydrogen evolution with increasing nitrogen content in the frameworks. Our results demonstrate that by the rational design of COFs on a molecular level, it is possible to precisely adjust their structural and optoelectronic properties, thus resulting in enhanced photocatalytic activities. This is expected to spur further interest in these photofunctional frameworks where rational supramolecular engineering may lead to new material applications.
authors.affiliation: Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany.
authors.forename: Vijay S
authors.initials: VS
authors.lastname: Vyas
authors.affiliation: Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany.|Department of Chemistry, University of Munich (LMU), Butenandtstr. 5-13, 81377 Munich, Germany.
authors.forename: Frederik
authors.initials: F
authors.lastname: Haase
authors.affiliation: Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany.|Department of Chemistry, University of Munich (LMU), Butenandtstr. 5-13, 81377 Munich, Germany.
authors.forename: Linus
authors.initials: L
authors.lastname: Stegbauer
authors.affiliation: Department of Chemistry, University of Munich (LMU), Butenandtstr. 5-13, 81377 Munich, Germany.
authors.forename: Gökcen
authors.initials: G
authors.lastname: Savasci
authors.affiliation: Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany.
authors.forename: Filip
authors.initials: F
authors.lastname: Podjaski
authors.affiliation: Department of Chemistry, University of Munich (LMU), Butenandtstr. 5-13, 81377 Munich, Germany.|Department of Chemistry, Center for Integrated Protein Science (CIPSM), University of Munich (LMU), Butenandtstrasse 5-13, 81377 Munich, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Ochsenfeld
authors.affiliation: Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany.|Department of Chemistry, University of Munich (LMU), Butenandtstr. 5-13, 81377 Munich, Germany.|Nanosystems Initiative Munich (NIM) and Center for Nanoscience, Schellingstr. 4, 80799 Munich, Germany.
authors.forename: Bettina V
authors.initials: BV
authors.lastname: Lotsch