We define a nomenclature for the classification of porous organic cage molecules, enumerating the 20 most probable topologies, 12 of which have been synthetically realised to date. We then discuss the computational challenges encountered when trying to predict the most likely topological outcomes from dynamic covalent chemistry (DCC) reactions of organic building blocks. This allows us to explore the extent to which comparing the internal energies of possible reaction outcomes is successful in predicting the topology for a series of 10 different building block combinations.
The hydrogen evolution activity of a polymeric photocatalyst was maximised by co-polymerisation, using both experimental and computational screening for a family of 1,4-phenylene/2,5-thiophene co-polymers.
We have investigated the suitability
of Time-Dependent Density
Functional Theory (TD-DFT) to describe vertical low-energy excitations
in naked and hydrated titanium dioxide nanoparticles. Specifically,
we compared TD-DFT results obtained using different exchange-correlation
(XC) potentials with those calculated using Equation-of-Motion Coupled
Cluster (EOM-CC) quantum chemistry methods. We demonstrate that TD-DFT
calculations with commonly used XC potentials (e.g., B3LYP) and EOM-CC
methods give qualitatively similar results for most TiO2 nanoparticles investigated. More importantly, however, we also show
that, for a significant subset of structures, TD-DFT gives qualitatively
different results depending upon the XC potential used and that only
TD-CAM-B3LYP and TD-BHLYP calculations yield results that are consistent
with those obtained using EOM-CC theory. Moreover, we demonstrate
that the discrepancies for such structures originate from a particular
combination of defects that give rise to charge-transfer excitations,
which are poorly described by XC potentials that do not contain sufficient
Hartree–Fock like exchange. Finally, we consider that such
defects are readily healed in the presence of ubiquitously present
water and that, as a result, the description of vertical low-energy
excitations for hydrated TiO2 nanoparticles is nonproblematic.
A structurally
diverse family of 39 covalent triazine-based framework materials (CTFs) are synthesized by Suzuki–Miyaura
polycondensation and tested as hydrogen evolution photocatalysts using
a high-throughput workflow. The two best-performing CTFs are based
on benzonitrile and dibenzo[b,d]thiophene
sulfone linkers, respectively, with catalytic activities that are
among the highest for this material class. The activities of the different
CTFs are rationalized in terms of four variables: the predicted electron
affinity, the predicted ionization potential, the optical gap, and
the dispersibility of the CTFs particles in solution, as measured
by optical transmittance. The electron affinity and dispersibility
in solution are found to be the best predictors of photocatalytic
hydrogen evolution activity.
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