Here, we reported the photophysical studies, single-crystal X-ray crystallography, and density functional theory (DFT) calculations of two bipyridine derivative molecules. In addition, thermal gravimetric analysis and cyclic voltammetry studies were also performed for both compounds. According to crystallographic data, the π-conjugated molecules have high-quality crystal structures as a result of intramolecular and intermolecular hydrogen bonds occurring through the molecules of the compound. It was determined that when the functional groups (F– and CH3O−) were introduced to the para positions, the molecules adopted slipped stacking (J-aggregate) and antiparallel cofacial stacking (H-aggregate). It was observed that these two bipyridine derivatives disclose the relationship between molecular conformation-molecular packing modes and photophysical behavior of organic solids. The results of DFT calculations supported the structural, spectroscopic, and photophysical data and confirmed the compositions of frontier molecular orbitals in both molecules.

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Red shift in the emission wavelength by 149 nm as a result of increased solvent polarity.

Self-assembled monolayers (SAMs) are well-oriented molecular structures that are formed by the adsorption of an active site of a surfactant onto a substrate's surface. Aromatic SAMs were used to modify anode/hole transport layer interface in order to achieve preferable barrier alignment and charge carrier injection from anode to an organic-based thin film material. Other functions of SAMs include current blocking layers or moisture penetration blocking layers, dipolar surface layers for enhanced charge injection, and modification of work function of a material such as graphene acting as a spacer to physically separate and electrically decouple it from the substrate. Additionally, SAM modification of graphene leads to its electronic passivation at layers' edges, elimination of defects, and enhanced adhesion and stability. The surface modification with molecules capable of forming SAM is a fast, simple, low-cost, and effective technique for the development of novel materials especially for the production of electronic devices. The ability to modify its properties by SAM technique has opened up a wide range of applications in electronic and optoelectronic devices.

In this paper, synthesis of high-quality large area graphene and alteration of its electrical properties by a non-covalent doping method via boronic acid-based organic small molecules were reported. A chemical vapor deposition method was used for large area graphene synthesis. In order to modify electrical properties of graphene, 3,5-difluorophenyl boronic acid and 3,4,5-trimethoxyphenyl boronic acid organic molecules have been used. The structural data and the energy level of molecules were obtained from density functional theory-based computational simulations. The electrical properties of doped and undoped graphene films were examined by Hall-effect measurement. It has been found that the density of charge carrier changes after doping due to the nature of molecules. Our results show that the electrical properties of graphene can effectively be manipulated via doping by phenylboronic compounds opening possibilities of application in electronics and optoelectronics for graphene.