Bo-Chao Lin

Synthesis and Isolation of an Acyclic Tridentate Bis(pyridine)carbodicarbene and Studies on Its Structural Implications and Reactivities

The simple synthetic development of acyclic pincer bis(pyridine)carbodicarbene is depicted herein. Presented is the first isolated structural pincer carbodicarbene with a C-C-C angle of 143°, larger than the monodentate framework. More importantly, theoretical analysis showed that this carbodicarbene embodies a more allene-like character. Palladium complexes supported by this pincer ligand are active catalysts for Heck-Mizoroki and Suzuki-Miyaura coupling reactions.

The Elusive Three-Coordinate Dicationic Hydrido Boron Complex

The formation of a hitherto unknown three-coordinate dicationic hydrido boron complex is described. Interestingly, supporting ligand carbodicarbene gave unprecedented reaction with BH3 without using more highly electrophilic Lewis acid precursors. Spectroscopic, crystallographic, and computational analysis was performed to understand the electronic features of these species.

Synthesis of planar dibenzo[de,op]bistetracene derivatives for organic field-effect transistor applications: substituent effect on crystal packing and charge transport property

A series of substituted dibenzo[de,op]bistetracenes (DBBTs) is prepared in short steps and their applications to organic field-effect transistors (OFETs) are described. These DBBT derivatives bear one or two methyl-, tert-butyl-, or fluoro groups at the 2-, 10-positions. X-ray diffraction studies reveal that the molecular structures of these DBBTs were planar with a shifted π–π stacking or herringbone-stacked type packing in the crystalline state. These substituents perturb the degree of stacking shift because of the steric effect and dipolar interaction, consequently affecting the electronic coupling between the neighboring molecules. Needle-like single crystals of DBBT derivatives were prepared by the vapor phase transfer method and used for the fabrication of single-crystal field-effect transistors (SCFETs). Theoretical calculation on these DBBTs has been performed to correlate the measured field-effect mobility with their molecular packing. The SCFET of di-methyl derivative 4b showed the highest hole mobility (1.19 cm2 V−1 s−1) with a current on/off ratio of 106.

Contorted tetrabenzoacenes of varied conjugation: charge transport study with single-crystal field-effect transistors

A series of contorted and polyfused aromatic tetrabenzoacene derivatives differing in conjugation length were synthesized and characterized. X-ray diffraction revealed the contorted molecular shape, as well as the packing arrangement of these molecules. Thus unsubstituted tetrabenzoacenes showed a shifted or perfect face-to-face π-stacking depending on their conjugation length. The single crystals of these tetrabenzoacenes were used as conducting channels in fabricating field-effect transistors (SCFETs). Tetrabenzotetracene (TBT) exhibited the highest measured mobility, approaching 0.81 cm2 V−1 s−1 (average 0.64 cm2 V−1 s−1) among these molecules. In contrast, theoretical calculation showed that the tetrabenzooctacene (TBO) crystal has large-area, face-to-face π-packing, with the highest intermolecular coupling in the series. The lower charge mobility (average 0.32 cm2 V−1 s−1, highest 0.55 cm2 V−1 s−1) observed was rationalized as a result of possible involvement of delocalized polaron formation due to comparable electronic coupling and reorganization energy in TBO, as supported by the Monte Carlo simulation with this delocalized effect taken into account.

Face-to-Face Packing of 2,3,9,10-Tetrasubstituted Pentacene Derivatives Revealed through a Solid State [4 + 4] Thermal Cycloaddition and Molecular Dynamic Simulation

2,3,9,10-Substituted pentacene tetraesters and pentacene diester-dinitriles were synthesized. These pentacene derivatives underwent an unusual solid state [4 + 4] thermal dimerization with good efficiency and complete stereoselectivity. This observation indicates this series of pentacene derivatives adopt π-π stacking geometry with large mutual overlap in solid state. This notion was confirmed by molecualr dynamic simulation.

One‐Pot Tandem Photoredox and Cross‐Coupling Catalysis with a Single Palladium Carbodicarbene Complex

The combination of conventional transition-metal-catalyzed coupling (2 e- process) and photoredox catalysis (1 e- process) has emerged as a powerful approach to catalyze difficult cross-coupling reactions under mild reaction conditions. Reported is a palladium carbodicarbene (CDC) complex that mediates both a Suzuki-Miyaura coupling and photoredox catalysis for C-N bond formation upon visible-light irradiation. These two catalytic pathways can be combined to promote both conventional transition-metal-catalyzed coupling and photoredox catalysis to mediate C-H arylation under ambient conditions with a single catalyst in an efficient one-pot process.