Boron‐Thioketonates: A New Class of S,O‐Chelated Boranes as Acceptors in Optoelectronic Devices

Abstract

Development of new n‐type semiconductors with tunable band gap and dielectric constant has significant implication in dissociating bound charge carrier relevant for demonstrating high performance optoelectronic devices. Boron‐β‐thioketonates (MTDKB), analogues to boron‐β‐diketonates containing a sulfur atom in the framework of β‐diketones were synthesized. Bulk transport measurement exhibited an outstanding bulk electron mobility of ≈0.003 cm2 V−1 s−1, which is among the best values reported till date in these class of semiconducting materials and correspondingly a single junction photo responsivity of upto 6 mA W−1 was obtained. This new family of O,S‐chelated boron compounds exhibited luminescence in the far red/near‐infrared region. The remarkable red shift of 89 nm (fluorescence) observed for 4 a in comparison with analogues boron‐β‐diketonate signifies the importance of sulfur in these molecules. MTDKBs with amine functionality have also been investigated as an ON/OFF fluorescent sensor.

Red-Emitting Tetraphenylethylene-Based Boron Thioketonates: Effect of Substitution and Study of Nonlinear Optical Properties

“…The observed B–S bond lengths (1.936(3) for 6 , 1.952(4) for 7 , and 1.957(3) for 8 ) are significantly longer than typical B–S single (1.89 Å) and B–S double bonds (1.69). , The C–S bond distances (1.718(3) for 6 ; 1.726(4) for 7 and 1.738(3) for 8 ) are longer than that observed in Ph 2 CS (1.636­(9) Å) . The B–O bond distances and S–B–O bond angles are comparable to other monothio-β-diketonate boron compounds reported in the literature. , In all three compounds, the six-membered ring formed by the boron coordination takes a twisted conformation, and the boron atom deviates from the plane C by 0.66, 0.52, and 0.56 Å for compounds 6 – 8 , respectively. The angle between plane A and plane C varies from 15.35 to 35.34°, and that of plane B and plane C varies from 11.54 to 15.04° (Table ).…”

“…The boron monothio-β-diketonate compounds 5−8 were synthesized by refluxing B(C 6 F 5 ) 3 and tetraphenylethylene (TPE) and N,N-dimethylaniline (DMA) derivatives of 1,3monothio-β-diketones (1−4) in dry toluene at 110 °C, as shown in Scheme 1. 35,52 The ligands 1−4 were synthesized by adopting a similar protocol as reported in the literature. 53 The synthesized ligands (1−4) and the boron compounds Single crystals of boron compounds 6−8 suitable for X-ray diffraction were grown by slow evaporation of the respective compounds from a mixture of solvents (6 and 7 from CHCl 3 / n-hexane mixture; 8 from CH 2 Cl 2 /diethyl ether mixture).…”

“…The boron monothio-β-diketonate compounds 5–8 were synthesized by refluxing B­(C 6 F 5 ) 3 and tetraphenylethylene (TPE) and N , N -dimethylaniline (DMA) derivatives of 1,3-monothio-β-diketones ( 1–4 ) in dry toluene at 110 °C, as shown in Scheme . , The ligands 1–4 were synthesized by adopting a similar protocol as reported in the literature . The synthesized ligands ( 1–4 ) and the boron compounds ( 5–8 ) were characterized by multinuclear NMR spectroscopy, HRMS, and single-crystal X-ray diffraction in the case of 6–8 .…”

“…Much effort has been paid to tune the photophysical properties of boron-β-diketonates by chemically modifying the π-conjugation via the substituents. ,− For example, Fraser and co-workers explored the substituent effect of boron-β-diketonates and studied them as stimuli-responsive materials, , and Chujo and co-workers described the effect of B–F vs B–aryl. , More recently, Adachi and co-workers demonstrated the use of boron-β-diketonates as NIR emissive materials. , Furthermore, efforts have been made to tune the photophysical properties by replacing one or two of the oxygen atoms present in the diketone moiety. For instance, Gardinier and Chujo groups reported the synthesis of boron-β-ketoiminate and boron-β-diiminate compounds and their rich photophysical properties. − We recently reported the first synthesis of monothio-β-diketonate boron compounds and studied their applications in making organic electronics …”

“…Boron-containing luminescent materials, − especially four-coordinated boron-containing luminescent materials, − have attracted considerable interest in various fields such as photovoltaics, organic field-effect transistors, light-emitting devices, and sensors owing to their tuneable and strong absorption, emission and stability over three-coordinated boron compounds. − Among the different tetracoordinated boron-containing luminescent materials, boron-β-diketonates have been studied to a greater extent due to their large molar extinction coefficients and high fluorescence quantum yields. Much effort has been paid to tune the photophysical properties of boron-β-diketonates by chemically modifying the π-conjugation via the substituents. ,− For example, Fraser and co-workers explored the substituent effect of boron-β-diketonates and studied them as stimuli-responsive materials, , and Chujo and co-workers described the effect of B–F vs B–aryl. , More recently, Adachi and co-workers demonstrated the use of boron-β-diketonates as NIR emissive materials. , Furthermore, efforts have been made to tune the photophysical properties by replacing one or two of the oxygen atoms present in the diketone moiety. For instance, Gardinier and Chujo groups reported the synthesis of boron-β-ketoiminate and boron-β-diiminate compounds and their rich photophysical properties. − We recently reported the first synthesis of monothio-β-diketonate boron compounds and studied their applications in making organic electronics …”