Intramolecular excited proton transfer of 1-(1-phenyl-1H-phenanthro[9,10-d]imidazol-2-yl)naphthalen-2-ol--a combined experimental and quantum chemical studies

A 1-Hydroxy-1H-imidazole ESIPT Emitter Demonstrating anti-Kasha Fluorescence and Direct Excitation of a Tautomeric Form

The ability of 1-hydroxy-1H-imidazoles to exist in the form of two prototropic tautomers, the N-hydroxy and the N-oxide forms, can be utilized in the design of new types of ESIPT-fluorophores (ESIPT=excited state intramolecular proton transfer). Here we report the first example of 1-hydroxy-1H-imidazole-based ESIPT-fluorophores, 1-hydroxy-5-methyl-2,4-di(pyridin-2-yl)-1H-imidazole (HL), featuring a short intramolecular hydrogen bond O-H⋅⋅⋅N (O⋅⋅⋅N 2.56 Å) as a pre-requisite for ESIPT. The emission of HL originates from the anti-Kasha S₂ →S₀ fluorescence in the N-oxide form as a result of a large S₂ -S₁ energy gap slowing down the S₂ →S₁ internal conversion. Due to an energy barrier between the N-hydroxy and N-oxide forms in the ground state, the HL molecules can be trapped and photoexcited in the N-oxide form leading to the Stokes shift of ca. 60 nm which is the smallest among known ESIPT-fluorophores.

Fused Methoxynaphthyl Phenanthrimidazole Semiconductors as Functional Layer in High Efficient OLEDs

Efficient hole transport materials based on novel fused methoxynaphthyl phenanthrimidazole core structure were synthesised and characterized. Their device performances in phosphorescent organic light emitting diodes were investigated. The high thermal stability in combination with the reversible oxidation process made promising candidates as hole-transporting materials for organic light-emitting devices. Highly efficient Alq3-based organic light emitting devices have been developed using phenanthrimidazoles as functional layers between NPB [4,4-bis(N-(1-naphthyl)-N-phenylamino)biphenyl] and Alq3 [tris(8-hydroxyquinoline)aluminium] layers. Using the device of ITO/NPB/4/Alq3/LiF/Al, a maximum luminous efficiency of 5.99 cd A(-1) was obtained with a maximum brightness of 40,623 cd m(-2) and a power efficiency of 5.25 lm W(-1).

Synthesis and optical properties of phenanthromidazole derivatives for organic electroluminescent devices

The external quantum efficiency roll-off may be due to triplet–triplet annihilation (TTA) and triplet–polaron annihilation (TPA).

ESIPT inspired dual fluorescent probe (Z)-3-((4-(4-aminobenzyl) phenyl) amino)-1,3-diphenylprop-2-en-1-one: experimental and DFT based approach to photophysical properties

A fluorescent probe (Z)-3-((4-(4-aminobenzyl) phenyl) amino)-1,3-diphenylprop-2-en-1-one (L) was synthesized and characterized by IR, (1)H NMR, ESI mass, UV-visible and fluorescence spectroscopy and by single crystal X-ray diffraction. The molecule has a stable helical structure due to intermolecular CH π interaction. The thermal stability of L was studied by TG analysis. The electronic structure calculations of L have been carried out using DFT at B3LYP/6-31G (d,p) level. The vibrational frequencies and (1)H NMR spectra were computed at this level and compared with experimental values. Major orbital contributions for the electronic transitions were assigned with the help of time-dependent density functional theory (TD-DFT). The observed electronic absorption spectra of L in different solvents coincide with the computed spectra in keto form. The dual emission and high Stokes shift values support the excited state intramolecular proton transfer (ESIPT) process. The molecular docking has been employed to get information about the interaction of L with DNA [6BNA].

Nano rutile TiO2 catalysed synthesis of (E)-4-(2-(1-(4-chlorophenyl)-1H-phenanthro[9,10-d]imidazol-2-yl)vinyl)-N,N-dimethylaniline and its interaction with super paramagnetic nanoparticles

The synthesis of (E)-4-(2-(1-(4-chlorophenyl)-1H-phenanthro[9,10-d]imidazol-2-yl)vinyl)-N,N-dimethylaniline (CPPIVI) has been carried out using TiO₂ (R) as catalyst under solvent free conditions and characterized by NMR spectral studies.