The design and characterization of thermally activated delayed fluorescence (TADF) materials for optoelectronic applications represents an active area of recent research in organoelectronics. Noble metal-free TADF molecules offer unique optical and electronic properties arising from the efficient transition and interconversion between the lowest singlet (S1) and triplet (T1) excited states. Their ability to harvest triplet excitons for fluorescence through facilitated reverse intersystem crossing (T1→S1) could directly impact their properties and performances, which is attractive for a wide variety of low-cost optoelectronic devices. TADF-based organic light-emitting diodes, oxygen, and temperature sensors show significantly upgraded device performances that are comparable to the ones of traditional rare-metal complexes. Here we present an overview of the quick development in TADF mechanisms, materials, and applications. Fundamental principles on design strategies of TADF materials and the common relationship between the molecular structures and optoelectronic properties for diverse research topics and a survey of recent progress in the development of TADF materials, with a particular emphasis on their different types of metal-organic complexes, D-A molecules, and fullerenes, are highlighted. The success in the breakthrough of the theoretical and technical challenges that arise in developing high-performance TADF materials may pave the way to shape the future of organoelectronics.

Thermally Activated Delayed Fluorescence Materials Towards the Breakthrough of Organoelectronics

Prediction of molecular properties and molecular spectroscopy with density functional theory: From fundamental theory to exchange-coupling

Potential energy surface crossings in organic photochemistry

Carbohydrate structural determination by NMR spectroscopy: modern methods and limitations

Many light-induced molecular processes involve a change in spin state and are formally forbidden in non-relativistic quantum theory. To make them happen, spin–orbit coupling (SOC) has to be invoked. Intersystem crossing (ISC), the nonradiative transition between two electronic states of different multiplicity, plays a key role in photochemistry and photophysics with a broad range of applications including molecular photonics, biological photosensors, photodynamic therapy, and materials science. Quantum chemistry has become a valuable tool for gaining detailed insight into the mechanisms of ISC. After a short introduction highlighting the importance of ISC and a brief description of the relativistic origins of SOC, this article focusses on approximate SOC operators for practical use in molecular applications and reviews state-of-the-art theoretical methods for evaluating ISC rates. Finally, a few sample applications are discussed that underline the necessity of studying the mechanisms of ISC processes beyond qualitative rules such as the El-Sayed rules and the energy gap law. © 2011 John Wiley & Sons, Ltd.

Spin–orbit coupling and intersystem crossing in molecules

Photoelektronenspektren organischer Verbindungen IX. Sterisch fixierte Bicyclopropyle

Vertical (PA v (B*)) and the adiabatic (PA a (B*)) proton affinities of the lowest excited π–π* singlet state are calculated for a series of monosubstituted benzenes Ph–X (XCHO, ( 1 ); XCOCH 3 , ( 2 ); XNO 2 , ( 3 ); XCN, ( 4 ); XNH 2 , ( 5 ) and XNO, ( 6 )) by applying CASPT2/6-31+G*//HF/6-31G* and CASPT2/6-31+G*//CIS/6-31+G* methods. Excited state proton affinities of 1 , 2 , 3 and 6 are found to be larger by 20–30 kcal/mol than in the S 0 states, while PAs of 4 and 5 appear to be of the same order of magnitude in both states. Geometrical relaxation leads in most cases to a slight increase in the PA(B*) values and does not influence relative basicity ordering across the series. Results are in reasonable agreement with the experimental data obtained by ICR technique.

Ab initio study of excited state protonation of monosubstituted benzenes

Theoretical study of the ring-opening reactions of 2H-azirines—a classification of substituent effects†

Aufgrund von PE-Spektren sowie aufgrund nach der MINDO/3-Methode berechneter Orbitalenergien und Bildungsenthalpien wird der Effekt einer moglichen Wechselwirkung zwischen dem freien Elektronenpaar des Stickstoffs und den π-Elektronen in 2-Azabicyclo[2.2.1]hept-5-en (2) und im N-Hydroxy-Derivat 4 diskutiert. MINDO/3-Rechnungen fur die entsprechenden Nitrenium-Ionen geben Hinweise auf den Mechanismus der Umlagerung der O-Tosylderivate von 4 und auf die Struktur der intermediar auftretenden Nitrenium- und Carbenium-Ionen.



MINDO/3 Calculations and PE Investigations on the Mode of the Reaction of Azabicyclic Compounds



On the basis of PE spectra as well as orbital energies and heats of formation calculated by means of the MINDO/3 method the effect of a possible interaction between the nitrogen lonepair and the π electrons in 2-azabicyclo[2.2.1]hept-5-ene (2) and its N-hydroxy derivative 4 is being discussed. MINDO/3 calculations for the corresponding nitrenium ions indicate a possible mechanism for the rearrangement reaction of the O-tosyl derivatives of 4 and for the structure of nitrenium and carbenium ions which should be intermediates for this mechanism.

MINDO/3‐Rechnungen und PE‐Untersuchungen zur Reaktionsweise von Azabicyclen

On discute sur la base de calculs INDO-SCPT de la dependance des couplages 13 C- 13 C a 3 liaisons des cis-butane et -butene avec les angles de valence et de torsion des groupes methyle et des substituants methyl et methylene

Martin Klessinger

Papers

Photoelektronenspektren organischer Verbindungen IX. Sterisch fixierte Bicyclopropyle

Ab initio study of excited state protonation of monosubstituted benzenes

Theoretical study of the ring-opening reactions of 2H-azirines—a classification of substituent effects†

MINDO/3‐Rechnungen und PE‐Untersuchungen zur Reaktionsweise von Azabicyclen

The structural dependence of vicinal 13C ? 13C coupling constants in s-cis-butane and cis-butane