Absorption Maxima Of Compounds Research Articles

An exploration of new avenues regarding deep tissue penetration and highersinglet oxygen efficiencies: novel near-IR photosensitizers for photodynamictherapy

A series of novel BODIPY-bearing electron-withdrawing groups at the meso position are reported here. According to the optical measurements, it may be clearly seen that the introduction of electron-donating groups into 3,5-positions and the presence of electron-withdrawing groups at the meso position of the BODIPY core resulted in spectacular bathochromic shifts (up to ∼ 304 nm), and the projected photosensitizers had absorption bands in the therapeutic window of the electromagnetic spectrum (600-900 nm). The absorption maxima of compounds 4,5,6, and 7 were at 886 nm, 890 nm, 760 nm, and 761 nm, respectively. The singlet oxygen generation experiments revealed that compounds 6 and 7, with high singlet oxygen quantum yields (0.52 and 0.93, respectively), were excellent and promising candidates for photodynamic therapy. The singlet oxygen quantum yield of 0.93 was the highest reported value so far for BODIPY-based photosensitizers.

Theoretical study on difunctional electroluminescent molecules containing aromatic heterocycle cores and hole-transporting triphenylamino units

2,2′-difuryl-4,4′-(N,N,N′,N′-tetraphenyl) diaminobiphenyl (FurylBz-Ph4) and 5,5′-bis(4-N,N′- diphenylaminophenyl)-2,2′-bifuryl (PFDA-Ph4) are new light-emitting materials, which are capable of transporting holes. A series of new compounds whose structures were similar to that of FurylBz-Ph4 or PFDA-Ph4, were designed and calculated. The total energies, HOMO and LUMO orbital energies of these compounds at neutral, cationic and anionic states were obtained based on the optimised geometrical structures. The ionization potential ( I p) and electron affinity ( E a) were generated by means of density functional theory (DFT) calculated total energy of neutral, cationic and anionic states. The reorganization energy for the hole transport of compounds 1- 3, FurylBz-Ph4 and PFDA-Ph4 is close to that of TPD at the same level of calculation. For compounds 2, 3 and PFDA-Ph4, the order of I p is 3 > PFDA-Ph4 > 2. It is indicated that the contribution of aryl groups to I p follows the sequence: thienyl > furyl > pyrryl. The absorptions of these compounds had been also investegated by time-dependent density functional theory (TD-DFT) methods with 6-31G(d) basis set. The TD-DFT calculations indicate that the absorption maximum of compounds 2 is blue-shifted from PFDA-Ph4, while the absorption maximum of compounds 3 is red-shifted from PFDA-Ph4. Since the electron-withdrawing strength is in the order pyrryl > thienyl > furyl and PFDA-Ph4 has the longer conjugated length between the two amine nitrogen atoms than that of compound 2 and 3. The different bands of emission and reorganization energy can be obtained by changing the substituents and the site of substitution between two triphenylamino units.

Molecular Design and Synthesis of Novel Analogues of Benzodixanthene and Anthradichromene

Molecular design of analogues of benzo [1,2,3-kl:4,5,6-k′l′]dixanthene and anthra[1,9-bc:4,10-b′c′]dichromene containing sulfur or nitrogen instead of oxygen was performed. The calculated absorption maxima of compounds containing oxygen or sulfur appeared in the similar region, while, those of their analogues containing nitrogen shifted to longer wavelengths. We have synthesized several new heterocyclic analogues and compared the observed wavelengths with the calculated ones.