Novel naphthalimide derivatives with near-infrared emission: synthesis via photochemical cycloaromatization, fluorescence in solvents and living cell

π-Extended fluoranthene imide derivatives: synthesis, structures, and electronic and optical properties

Diels–Alder reactions of acenaphthylene-5,6-dicarboximide (AI) derivatives with the corresponding dienes afforded some derivatives of π-extended fluoranthene imide, namely N-(2-ethylhexyl)-7,10-diphenylfluoranthene imide (DPFI) and N-(2-ethylhexyl)-7,8,9,10-tetraphenylfluoranthene imide (TPFI), N-(n-octyl)-benzo[k]fluoranthene imide (BFI), and N-(n-octyl)-naphtho[k]fluoranthene imide (NFI). Molecular structures of TPFI and BFI reveal that the core π-skeletons have a highly planar structure, and the molecules form a dimeric structure in the crystals. The absorption spectra exhibit bathochromic shift with π-extension of the core π-skeletons. On the other hand, DPFI and TPFI show the long-wavelength emission related to BFI, probably due to π-extension toward the phenyl substituents in the excited states. BFI and NFI exhibited an interesting concentration-dependent 1H-NMR behavior in CDCl3, suggesting self-aggregation formation. Moreover, BFI and NFI show moderate and remarkable solvatofluorochromism in solutions (BFI for ΔλEM = 67 nm, NFI for ΔλEM = 116 nm), respectively, while DPFI and TPFI show weak solvatofluorochromism. The density functional theory calculations demonstrate that the considerable spatial separation between the HOMO and LUMO coefficients in the NFI molecule. The result indicates that the ground-to-excited state transition of NFI should have intramolecular charge transfer (ICT) character.

Controlling photophysics of styrylnaphthalimides through TICT, fluorescence and E,Z-photoisomerization interplay

The steady-state and time-resolved spectral properties of styrylnaphthalimides are studied in various solvents.

Novel fluorescent 1,8-naphthalimide derivatives containing thiophene and pyrazole moieties: synthesis by direct C-H arylation and evaluation of photophysical and electrochemical properties

A series of novel 1,8-naphthalimide derivatives containing thiophene and pyrazole moities were synthesized by direct Pd-catalyzed C-H arylation and then characterized by (1)H NMR, (13)C NMR, MALDI-HRMS, and elementary analysis. The photophysical and electrochemical properties of the derivatives were also investigated. All compounds have green emission both in diluted CH2Cl2 solution and solid film. The cyclic voltammetry (CV) measurements showed that the target compounds had a lowest unoccupied molecular orbital (LUMO) range from -3.49 eV to -3.29 eV and a highest occupied molecular orbital (HOMO) range from -6.04 eV to -5.81 eV. Quantum chemical calculations were performed to obtain the optimized ground-state geometry as well as the spatial distributions of the HOMO, LUMO levels of the compounds.

Synthesis and anti-intestinal nematode activity of variously substituted benzonaphthyridine derivatives

A series of benzonaphthyridine derivatives bearing the C=N linkage moiety were designed and synthesized. The structures of all the newly synthesized compounds were identified by elemental analysis, ¹H-NMR, ¹³C-NMR and MS. Their anti-intestinal nematode activities against Nippostrongylus brazilliensis were evaluated in vivo by an oral route in male rats. Among these compounds, at concentrations of 10 mg/kg of rat, the compound 7-chloro-2-methoxy-10-(4-(4′-(1H-indol-5′-yl)methylene)aminophenyl)-amino-benzo[b][1,5] naphthyridine (4n) produced the highest activity, with 80.2% deparasitization. These compounds may find usefulness in the discovery and development of new anti-intestinal drugs.

Molecular rotors: Synthesis and evaluation as viscosity sensors

It has been shown that compounds containing the p-N,N,-dialkylaminobenzylidene cyanoacetate motif can serve as fluorescent non-mechanical viscosity sensors. These compounds, referred to as molecular rotors, belong to a class of fluorescent probes that are known to form twisted intramolecular charge-transfer complexes in the excited state. In this study we present the synthesis and spectroscopic characterization of these compounds as viscosity sensors. The effects of the molecular structure and electronic density of these rotors to the emission wavelength, fluorescence intensity and viscosity sensitivity are discussed.