Synthesis, electrochemistry and fluorescence behavior of thiophene derivatives decorated with coumarin, pyrene and naphthalene moieties

Theoretical Study on Non-Linear Optics Properties of Polycyclic Aromatic Hydrocarbons and the Effect of Their Intercalation with Carbon Nanotubes

Results of a theoretical study devoted to comparing NLO (non-linear optics) responses of derivatives of tetracene, isochrysene, and pyrene are reported. The static hyperpolarizability β, the dipole moment μ, the HOMO and LUMO orbitals, and their energy gap were calculated using the CAM-B3LYP density functional combined with the cc-pVDZ basis set. The para-disubstituted NO2-tetracene-N(CH3)2 has the highest NLO response, which is related to a large intramolecular charge transfer. Adding vinyl groups to the para-disubstituted NO2-tetracene-N(CH3)2 results in an increase in the NLO responses. We further investigated the effect of the intercalation of various push-pull molecules inside an armchair single-walled carbon nanotube. The intercalation leads to increased NLO responses, something that depends critically on the position of the guest molecule and/or on functionalization of the nanotube by donor and attractor groups.

Synthesis, Characterization and Luminescent Properties of Anthracen- or Pyrene-Based Coumarin Derivatives

Three anthracen- or pyrene-based coumarin derivatives have been successfully synthesized and characterized by EA, IR and ¹H NMR. The photophysical properties of all derivatives were investigated by UV-Vis and photoluminescence spectroscopic analysis. Their thermal stabilities were demonstrated by TGA. These compounds exhibit strong blue mission under ultraviolet light excitation and have potential possible to explore organic electroluminescent materials. The vacuum-processed doped devices with a configuration of ITO/TAPC (20 nm)/TBADN: b1 (x wt%, 30 nm)/TPBi (50 nm)/Liq (2 nm)/Al (150 nm) was fabricated, in which the devices based on b1 exhibited the best electroluminescence performance with a maximum brightness of 8165 cd/m² and a maximum luminous efficiencies of 6.13 cd/A and a maximum external quantum efficiency (EQE) of 2.75%.

Synthesis, in vitro β-glucuronidase inhibitory activity and in silico studies of novel (E)-4-Aryl-2-(2-(pyren-1-ylmethylene)hydrazinyl)thiazoles

Current research is based on the synthesis of novel (E)-4-aryl-2-(2-(pyren-1-ylmethylene)hydrazinyl)thiazole derivatives (3-15) by adopting two steps route. First step was the condensation between the pyrene-1-carbaldehyde (1) with the thiosemicarbazide to afford pyrene-1-thiosemicarbazone intermediate (2). While in second step, cyclization between the intermediate (2) and phenacyl bromide derivatives or 2-bromo ethyl acetate was carried out. Synthetic derivatives were structurally characterized by spectroscopic techniques such as EI-MS, ¹H NMR and ¹³C NMR. Stereochemistry of the iminic double bond was confirmed by NOESY analysis. All pure compounds 2-15 were subjected for in vitro β-glucuronidase inhibitory activity. All molecules were exhibited excellent inhibition in the range of IC₅₀=3.10±0.10-40.10±0.90μM and found to be even more potent than the standard d-saccharic acid 1,4-lactone (IC₅₀=48.38±1.05μM). Molecular docking studies were carried out to verify the structure-activity relationship. A good correlation was perceived between the docking study and biological evaluation of active compounds.

Performance of Hybrid DFT Compared to MP2 Methods in Calculating Nonlinear Optical Properties of Divinylpyrene Derivative Molecules

A series of divinyl-pyrene derivatives of the form D-vinyl-pyrene-vinyl-A, in which D corresponds to an electron donor group and A to an electron acceptor group, were studied in this work. The first purpose was to determine the optimal HF % exchange as incorporated in a range of hybrid functionals (M06HF, M062X, M06L, CAM-B3LYP, PBE0, BMK, and B3LYP) capable to produce, reliably and as close as possible to those obtained from MP2 calculations, NLO parameters and, in particular, first-order static hyperpolarizabilities. The CAM-B3LYP functional was revealed to be the most suitable one. The pair N(CH₃)₂/NO₂ was then determined as the most efficient pair of groups in producing appreciable NLO responses. The effect of the substitution position on the pyrene moiety was also investigated, whereby aligning the two substituents involving the D and A groups in the direction of the dipole moment as in the (1,6 DVP) derivatives was shown to be most favorable for increasing the NLO parameters.

Crystal structure of 2-(thio-phen-3-yl)ethyl pyrene-1-carboxyl-ate

In the title compound, C23H16O2S, the thio-phene group is rotationally disordered into two fractions almost parallel to each other, with occupation factors of 0.523 (7) and 0.477 (7), and subtending dihedral angles of 10.5 (5) and 9.3 (5)°, respectively, to the thio-phene group. The mol-ecules are held together by weak C-H⋯O and C-H⋯π hydrogen bonds, producing a laminar arrangement, which are further connected in a perpendicular fashion by S⋯π contacts [S⋯centroid = 3.539 (8) and 3.497 (8) Å]. In spite of the presence of the entended pyrene group, the structure does not present any parallel π-π stacking inter-actions. The structure was refined as an inversion twin.

Synthesis, crystal structures and photoluminescence of anthracen- and pyrene-based coumarin derivatives

Two new anthracen- and pyrene-based coumarin derivatives, 3-(4-(anthracen-10-yl)phenyl)coumarin (4) and 3-(4-(pyrene-1-yl)phenyl)coumarin (5), were synthesized and characterized by FT-IR, (1)H NMR, element analysis and single crystal X-ray crystallography. The UV-vis absorption and photoluminescence spectra of these coumarin derivatives were investigated. The results show that compound 4 and 5 exhibit blue and blue-green emissions, respectively, under ultraviolet light excitation. Compared with the compound 4, the emission peak of compound 5 was bathochromically shifted by about 80 nm due to the more planar structure and larger π-conjugation.

Crystal structure of 1,3-dicyclohexyl-1-[3-(pyren-1-yl)propanoyl]urea

In the title compound, C₃₃H₃₈N₂O₂, each of the cyclo­hexyl rings adopts a chair conformation. The two planes involving carbonyl groups, C—(C=O)—N and N—(C=O)—N, are oriented at a dihedral angle of 62.28 (10)°. In the crystal, two neighboring mol­ecules are linked by a pair of N—H⋯O inter­actions, generating an inversion dimer. The dimers are inter­connected by C—H⋯O hydrogen bonds into a supra­molecular chain along the a-axis direction.

Synthesis of dabsyl-appended cyclophanes and their heterodimer formation with pyrene-appended cyclophanes

As a quencher-type host, dabsyl-appended cyclophanes bearing positively and negatively charged side chains (1a and 1b, respectively) were synthesized. Formation of cyclophane heterodimers of 1a with anionic fluorescent cyclophane bearing a pyrene moiety 2b was confirmed by fluorescence titration experiments. The 1:1 binding constant (K) of 1a toward 2b was calculated to be 1.6 × 10(5) M(-1). On the other hand, almost no complexation affinity of 1a toward cationic analogue of fluorescent cyclophane 2a was confirmed by the identical methods, indicating that electrostatic interactions became effective in the formation of cyclophane heterodimers. In addition, van't Hoff analysis applied to the temperature-dependent K values for the heterodimer formation gave negative enthalpy (ΔH) and entropy changes (ΔS). The large and negative ΔH values as well as small and also negative ΔS values showed that the complexation is an exothermic and enthalpy-controlled but not entropy-driven process. A similar trend of molecular recognition was also confirmed for formation of cyclophane heterodimers of 1b with 2a by the identical methods.