The much-needed renewable alternatives to fossil fuel can be achieved efficiently and sustainably by converting solar energy to fuels via hydrogen generation from water or CO2 reduction. Herein, a soft processable metal-organic hybrid material is developed and studied for photocatalytic activity towards H2 production and CO2 reduction to CO and CH4 under visible light as well as direct sunlight irradiation. A tetrapodal low molecular weight gelator (LMWG) is synthesized by integrating tetrathiafulvalene (TTF) and terpyridine (TPY) derivatives through amide linkages and results in TPY-TTF LMWG. The TPY-TTF LMWG acts as a linker, and self-assembly of this gelator molecules with ZnII ions results in a coordination polymer gel (CPG); Zn-TPY-TTF. The Zn-TPY-TTF CPG shows high photocatalytic activity towards H2 production (530 μmol g−1h−1) and CO2 reduction to CO (438 μmol g−1h−1, selectivity > 99%) regulated by charge-transfer interactions. Furthermore, in situ stabilization of Pt nanoparticles on CPG (Pt@Zn-TPY-TTF) enhances H2 evolution (14727 μmol g−1h−1). Importantly, Pt@Zn-TPY-TTF CPG produces CH4 (292 μmol g−1h−1, selectivity > 97%) as CO2 reduction product instead of CO. The real-time CO2 reduction reaction is monitored by in situ DRIFT study, and the plausible mechanism is derived computationally.
A storable bicyclic (alkyl)(amino)carbene (BICAAC) stabilized two coordinate zinc(0) complex [(BICAAC)2Zn] (2) was synthesized. DFT calculations reveal that BICAAC plays decisive role for imparting the stability of 2. This complex...
Tetrel Lewis acids are a prospective
alternative to commonly employed
neutral boranes in frustrated Lewis pair (FLP) chemistry. While cationic
tetrylium Lewis acids, being isolobal and iso(valence)electronic,
are a natural replacement to boranes, neutral tetrel Lewis acids allude
as less trivial options due to the absence of a formally empty p orbital
on the acceptor atom. Recently, a series of intramolecular geminal
FLPs (C2F5)3E-CH2-P(tBu)2
(E = Si, Ge, Sn) featuring
neutral tetrel atoms as acceptor sites has been reported for activation
of small molecules including H2. In this work, through
density functional theory computations, we elucidate the general mechanistic
picture of H2 activation by this family of FLPs. Our findings
reveal that the acceptor atom derives the required Lewis acidity utilizing
the antibonding orbitals of its adjacent bonds with the individual
contributions depending on the identity of the acceptor and the donor
atoms. By varying the identity of the Lewis acid and Lewis base sites
and attached substituents, we unravel their interplay on the energetics
of the H2 activation. We find that switching the donor
site from P to N significantly affects the synchronous nature of the
bond breaking/formations along the reaction pathway, and as a result,
N-bearing FLPs have a more favorable H2 activation profile
than those with P. Our results are quantitatively discussed in detail
within the framework of the activation–strain model of reactivity
along with the energy-decomposition analysis method. Finally, the
reductive elimination decomposition route pertinent to the plausible
extension of the H2 activation to catalytic hydrogenation
by these FLPs is also examined.
An extended class of stable mesoionic N‐heterocyclic imines (mNHIs), containing a highly polarized exocyclic imine moiety, were synthesized. The calculated proton affinities (PA) and experimentally determined Tolman electronic parameters (TEPs) reveal that these synthesized mNHIs have the highest basicity and donor ability among NHIs reported so far. The superior nucleophilicity of newly designed mNHIs was utilized in devising a strategy to incorporate CO2 as a bridging unit under reductive conditions to couple inert primary amides. This strategy was further extended to hetero‐couplings between amide and amine using CO2. These hitherto unknown catalytic transformations were introduced in the diversification of various biologically active drug molecules under metal‐free conditions. The underlying mechanism was explored by performing a series of control experiments, characterizing key intermediates using spectroscopic and crystallographic techniques.
Strategic design to develop highly sensitive stimuli-responsive photoluminescence (PL)-switching materials are vastly preferred but hard to achieve. This work describes the design and straightforward economical synthesis of small, conformationally-twisted, and...
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