Tetraazaperopyrenes: A New Class of Multifunctional Chromophores

Abstract

Tetraazaperopyrene and a range of derivatives have been synthesised and their photophysical and redox-chemical properties studied. The parent compound, 1,3,8,10-tetraazaperopyrene (1), was prepared by treating 4,9-diamino-3,10-perylenequinone diimine with triethyl orthoformate, whereas the 2,9-disubstituted derivatives of 1 were obtained after treatment with the corresponding carboxylic acid chloride or anhydride (2 mol equiv). The 1,3,8,10-tetraazaperopyrene core structure was established by X-ray diffraction of 2,9-bis(2-bromophenyl)-1,3,8,10-tetraazaperopyrene (6). The UV-visible absorption spectra of the compounds have a characteristic visible pi(*)<--pi absorption band at 440 nm (log epsilon(max)=4.80) with a strong vibrational progression (Delta nu approximately 1450 cm(-1)). Diprotonation of the nitrogen atoms induces a bathochromic shift of this band from 430-440 to 470-480 nm and all four nitrogen atoms are protonated when pure H(2)SO(4) is used as the solvent. The first and second as well as the third and fourth protonations occur concomitantly, which implies that they have very similar pK(a) values and, consequently, similar proton affinities. A theoretical study of the proton affinities in the gas phase and in solution attributes this behaviour to the effects of polar solvents, which dampen the charge of a protonated site at the other end of the molecule and thus effectively decouple the two opposite pyrimidine units in the polycondensed aromatic compound. The photophysical data were modelled in a time-dependent DFT study of 1, 1H(2)(2+) and 1H(4)(4+) in both the gas phase and in a polar solvent. All the dyes show weak fluorescence in organic solvents, however, their protonated conjugate acids show dramatically increased fluorescence intensity. All of the dyes undergo two electrochemically reversible one-electron reductions with cyclovoltammetric half-wave potentials at E(red1) approximately -0.9 V and E(red2) approximately -1.3 V (vs. SCE), which are associated with characteristic spectral changes.

Aggregation and Contingent Metal/Surface Reactivity of 1,3,8,10‐Tetraazaperopyrene (TAPP) on Cu(111)

“…The CuA C H T U N G T R E N N U N G (111) single crystal was prepared by subsequent cycles of sputtering with Ar + ions and annealing at approximately 500 8C. TAPP [20] was deposited on the metal surface from a glass crucible that was heated inside a commercial evaporator (Kentax UHV equipment) while the rate was controlled by a quartz crystal microbalance (QMB).…”

“…Recently we reported the synthesis of 1,3,8,10-tetraazaperopyrene (TAPP), [20] a condensed poly-N-heterocyclic aromatic compound, which contains four potentially metal-ligating exodentate N-donor functions that are symmetrically arranged with respect to the principal molecular axis (Figure 1). Additionally, the C À H bridge between the two nitrogen atoms offers the potential of tautomerisation to an N-heterocyclic carbene isomer, or may undergo metal-induced C À H activation at elevated temperatures.…”

Synthesis and Characterization of 2‐Mono‐ and 1,2‐Diaminocarba‐closo‐dodecaborates M[1‐R‐2‐H2N‐closo‐CB11H10] (R=H, Ph, H2N, CyHN)

“…Thermodynamic cycle for the calculation of the pK a values. [80,94] www.chemeurj.org been calculated according to Equation (7): [95] PA…”

Core Halogenation as a Construction Principle in Tuning the Material Properties of Tetraazaperopyrenes

“…In recent years we developed the synthesis of 1,3,8,10‐tetraazaperopyrenes (TAPP), a new class of polyheterocyclic aromatics 31. 32 TAPP derivatives have shown promising results as both fluorescence markers and organic semiconductors 33–35.…”