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  1. A longstanding challenge in the field of optoelectronic materials, the effects of solid-state arrangement and morphology are still a prominent factor associated with small-molecule and polymer-based device performance. Here, mixed heterocyclic aromatic oligomers containing thiophene, furan and pyrazine are prepared alongside their methylated congeners. Their solution and solid-phase properties were studied via spectroscopic, electrochemical and single-crystal X-ray diffraction (XRD) analysis. Comparative analysis between solid-state packing arrangements and photophysical properties revealed optical band gaps as low as 1.7 eV with Stokes-shifts up to 130 nm and quantum yields of 12%. Results of the study aid in further understanding the effects of molecular and solid-state arrangements that give rise to unique optical and photophysical properties critical to enhancing optoelectronic behavior.
    Free, publicly-accessible full text available June 27, 2023
  2. Guided by computational analysis, herein we report the design, synthesis and evaluation of four novel diazine-based histone deacetylase inhibitors (HDACis). The targets of interest (TOI) are analogues of panobinostat, one of the most potent and versatile HDACi reported. By simply replacing the phenyl core of panobinostat with that of a diazine derivative, docking studies against HDAC2 and HDAC8 revealed that the four analogues exhibit inhibition activities comparable to that of panobinostat. Multistep syntheses afforded the visualized targets TOI1 , TOI2 , TOI3-rev and TOI4 whose biological evaluation confirmed the strength of HDAC8 inhibition with TOI4 displaying the greatest efficacy at varying concentrations. The results of this study lay the foundation for future design strategies toward more potent HDACis for HDAC8 isozymes and further therapeutic applications for neuroblastoma.
  3. Two new aromatic pyrimidine-based derivatives designed specifically for halogen bond directed self-assembly are investigated through a combination of high-resolution Raman spectroscopy, X-ray crystallography, and computational quantum chemistry. The vibrational frequencies of these new molecular building blocks, pyrimidine capped with furan (PrmF) and thiophene (PrmT), are compared to those previously assigned for pyrimidine (Prm). The modifications affect only a select few of the normal modes of Prm, most noticeably its signature ring breathing mode, ν1. Structural analyses afforded by X-ray crystallography, and computed interaction energies from density functional theory computations indicate that, although weak hydrogen bonding (C–H···O or C–H···N interactions) is present in these pyrimidine-based solid-state co-crystals, halogen bonding and π-stacking interactions play more dominant roles in driving their molecular-assembly.
  4. Block copolymers comprising benzothiadiazole were successfully electro-copolymerized leading to (BTD-T 2 ) n (BTD-F 2 ) m , where n and m were varied in a perfectly controllable, well-defined manner. The polymers were characterized by cyclic voltammetry, AC-impedance, SEM–EDAX and XPS analyses. They exhibit absorbance and emission in the near infrared (NIR) region. Results support an efficient strategy towards the creation of even more complex materials with innumerable possible applications in optoelectronic.
  5. Recent advancements in material science exploit non-covalent interactions, such as halogen bonding (XB) or π-stacking within solid-state molecular frameworks for application in organic electronic devices. Herein, we focus on these and other non-covalent interactions and the effect that furan and thiophene substituents play on the solid-state properties of co-crystals formed between pentafluoro(iodoethynyl)benzene ( F 5 BAI ; XB donor) and a pyridine disubstituted with either furans or thiophenes ( PyrFur 2 and PyrThio 2 ; XB acceptors). Spectroscopic and thermal analyses of 1 : 1 mixtures provide indirect evidence of XB interactions, whereas X-ray crystallography provides direct evidence that XB and π-stacking are present in both co-crystals. Density functional theory (DFT) computations provide insight into the relative electronic energetics of each pair-wise contact observed in the experimental F 5 BAI-PyrFur 2 and F 5 BAI-PyrThio 2 co-crystals.
  6. Iodine binding to thiophene rings in dyes for dye-sensitized solar cells (DSCs) has been hypothesized to be performance degrading in a number of literature cases. Binding of iodine to dyes near the semiconductor surface can promote undesirable electron transfers and lower the overall efficiency of devices. Six thiophene or furan containing dye analogs were synthesized to analyze iodine binding to the dyes via Raman spectroscopy, UV-Vis studies, device performance metrics and density functional theory (DFT) based computations. Evidence suggests I 2 binds thiophene-based dyes stronger than furan-based dyes. This leads to higher DSC device currents and voltages from furan analogues, and longer electron lifetimes in DSC devices using furan based dyes. Raman spectrum of the TiO 2 surface-bound dyes reveals additional and more instense peaks for thiophene dyes in the presence of I 2 relative to no I 2 . Additionally, broader and shifted UV-Vis peaks are observed for thiophene dyes in the presence of I 2 on TiO 2 films suggesting significant interaction between the dye molecules and I 2 . These observations are also supported by DFT and TD-DFT calculations which indicate the absence of a key geometric energy minimum in the dye–I 2 ground state for furanmore »dyes which are readily observed for the thiophene based analogues.« less