: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

C–H activation has surfaced as an increasingly powerful tool for molecular sciences, with notable applications to material sciences, crop protection, drug discovery, and pharmaceutical industries, among others. Despite major advances, the vast majority of these C–H functionalizations required precious 4d or 5d transition metal catalysts. Given the cost-effective and sustainable nature of earth-abundant first row transition metals, the development of less toxic, inexpensive 3d metal catalysts for C–H activation has gained considerable recent momentum as a significantly more environmentally-benign and economically-attractive alternative. Herein, we provide a comprehensive overview on first row transition metal catalysts for C–H activation until summer 2018.

3d Transition Metals for C-H Activation.

Light-Emitting Self-Assembled Materials Based on d(8) and d(10) Transition Metal Complexes.

Triplet photosensitizers (PSs) are compounds that can be efficiently excited to the triplet excited state which subsequently act as catalysts in photochemical reactions. The name is originally derived from compounds that were used to transfer the triplet energy to other compounds that have only a small intrinsic triplet state yield. Triplet PSs are not only used for triplet energy transfer, but also for photocatalytic organic reactions, photodynamic therapy (PDT), photoinduced hydrogen production from water and triplet-triplet annihilation (TTA) upconversion. A good PS should exhibit strong absorption of the excitation light, a high yield of intersystem crossing (ISC) for efficient production of the triplet state, and a long triplet lifetime to allow for the reaction with a reactant molecule. Most transition metal complexes show efficient ISC, but small molar absorption coefficients in the visible spectral region and short-lived triplet excited states, which make them unsuitable as triplet PSs. One obstacle to the development of new triplet PSs is the difficulty in predicting the ISC of chromophores, especially of organic compounds without any heavy atoms. This review article summarizes some molecular design rationales for triplet PSs, based on the molecular structural factors that facilitate ISC. The design of transition metal complexes with large molar absorption coefficients in the visible spectral region and long-lived triplet excited states is presented. A new method of using a spin converter to construct heavy atom-free organic triplet PSs is discussed, with which ISC becomes predictable, C60 being an example. To enhance the performance of triplet PSs, energy funneling based triplet PSs are proposed, which show broadband absorption in the visible region. Applications of triplet PSs in photocatalytic organic reactions, hydrogen production, triplet-triplet annihilation upconversion and luminescent oxygen sensing are briefly introduced.

Triplet photosensitizers: from molecular design to applications

The present review is devoted to summarizing the recent advances (2015-2017) in the field of metal-catalysed group-directed C-H functionalisation In order to clearly showcase the molecular diversity that can now be accessed by means of directed C-H functionalisation, the whole is organized following the directing groups installed on a substrate Its aim is to be a comprehensive reference work, where a specific directing group can be easily found, together with the transformations which have been carried out with it Hence, the primary format of this review is schemes accompanied with a concise explanatory text, in which the directing groups are ordered in sections according to their chemical structure The schemes feature typical substrates used, the products obtained as well as the required reaction conditions Importantly, each example is commented on with respect to the most important positive features and drawbacks, on aspects such as selectivity, substrate scope, reaction conditions, directing group removal, and greenness The targeted readership are both experts in the field of C-H functionalisation chemistry (to provide a comprehensive overview of the progress made in the last years) and, even more so, all organic chemists who want to introduce the C-H functionalisation way of thinking for a design of straightforward, efficient and step-economic synthetic routes towards molecules of interest to them Accordingly, this review should be of particular interest also for scientists from industrial R&D sector Hence, the overall goal of this review is to promote the application of C-H functionalisation reactions outside the research groups dedicated to method development and establishing it as a valuable reaction archetype in contemporary R&D, comparable to the role cross-coupling reactions play to date

/pdf/a-comprehensive-overview-of-directing-groups-applied-in-543u6d0g60.pdf

A comprehensive overview of directing groups applied in metal-catalysed C-H functionalisation chemistry.

The first highly efficient and scalable cobalt-catalyzed directed C-H functionalization with carbene precursors is presented. This methodology provides a modular route towards a new class of conjugated polycyclic hydrocarbons with tunable emission wavelengths both in solution and in the solid state.

Cobalt(III)-Catalyzed Directed C ? H Coupling with Diazo Compounds: Straightforward Access towards Extended π-Systems

Triplet emitters based on platinum(II) complexes have gained major attention in recent times. They can form aggregates or excimers, causing shifts in the emitted wavelengths and affecting the photoluminescence quantum yields (PLQYs). Even though this effect can be exploited for the construction of white organic light emitting diodes (WOLEDs), it is disadvantageous for applications where color purity is desirable. Terpyridine ligands and their N^C^N and N^N^C analogues have been coordinated to platinum(II), leading to neutral, mono-, or doubly charged species, some of which display bright luminescence. They can form supramolecular structures, such as nanowires, nanosheets, and polymeric mesophases, with interesting optical properties. For low-molecular-weight organoor hydrogelators, the operating mechanism of gelation has been recognized as a supramolecular effect, where the constituting fibers, usually of microscale lengths and nanoscale diameters, are formed in solution predominantly by unidirectional self-assembly. The entanglement of filaments gives a network that entraps solvent molecules within the compartments. As supramolecular gels provide fibrous aggregates with long-range order, they could be of interest in the fields of optoelectronic devices and sensors. In this context, organometallic gelators can display metal–metal interactions that influence their properties. Herein we present a straightforward one-pot synthesis of neutral, soluble platinum(II) coordination compounds bearing a dianionic tridentate terpyridine-like ligand. The coordination of an alkyl pyridine ancillary moiety to the 2,6bis(tetrazolyl)pyridine complex allowed us to enhance the solubility and thus the processability. The synthetic approach involved mild reaction conditions that involved a nonnucleophilic base and an adequate inorganic platinum(II) precursor. Moistureand oxygen exclusion were not required, and the product was easily purified by repeated precipitation (Scheme 1). The emission intensity of the complex attained a

https://ir.nctu.edu.tw:443/bitstream/11536/26094/1/000287157600030.pdf

Switching on luminescence by the self-assembly of a platinum(II) complex into gelating nanofibers and electroluminescent films.

Photoactive hybrid nanomaterial for targeting, labeling, and killing antibiotic-resistant bacteria.

Two tetraphenylethylene (TPE) bridged tetraimidazolium salts, [H4 L-Et](PF6 )4 and [H4 L-Bu](PF6 )4 , were used as precursors for the synthesis of the dinuclear AgI and AuI tetracarbene complexes [Ag2 (L-Et)](PF6 )2 , [Ag2 (L-Bu)](PF6 )2 , [Au2 (L-Et)](PF6 )2 , and [Au2 (L-Bu)](PF6 )2 . The tetraimidazolium salts show almost no fluorescence (ΦF <1 %) in dilute solution while their NHC complexes display fluorescence "turn-on" (ΦF up to 47 %). This can be ascribed to rigidification mediated by the restriction of intramolecular rotation within the TPE moiety upon complexation. DFT calculations confirm that the metals are not involved in the lowest excited singlet and triplet states, thus explaining the lack of phosphorescence and fast intersystem crossing as a result of heavy atom effects. The rigidification upon complexation for fluorescence turn-on constitutes an alternative to the known aggregation-induced emission (AIE).

Turn-On Fluorescence in Tetra-NHC Ligands by Rigidification through Metal Complexation: An Alternative to Aggregation-Induced Emission.

The first CH bond activation with pyridotriazoles as coupling partners is presented using a RhIII catalyst. The pyridotriazoles can be used as new carbene precursors in CH activation for direct access to novel fluorescent scaffolds. These tunable fluorophores can be applied for the detection of metal ions.

Cristian A. Strassert

Papers

Cobalt(III)-Catalyzed Directed C ? H Coupling with Diazo Compounds: Straightforward Access towards Extended π-Systems

Switching on luminescence by the self-assembly of a platinum(II) complex into gelating nanofibers and electroluminescent films.

Photoactive hybrid nanomaterial for targeting, labeling, and killing antibiotic-resistant bacteria.

Turn-On Fluorescence in Tetra-NHC Ligands by Rigidification through Metal Complexation: An Alternative to Aggregation-Induced Emission.

RhIII‐Catalyzed CH Activation with Pyridotriazoles: Direct Access to Fluorophores for Metal‐Ion Detection