Hydrogenated tetraazaporphyrins—old but new core-modified phthalocyanine analogues

Abstract

The synthesis, and spectroscopic and electrochemical properties of hydrogenated tetraazaporphyrins (TAPs), namely tetraazachlorins (TACs), tetraazabacteriochlorins (TABCs) and tetraazaisobacteriochlorins (TAiBCs), have been reviewed. While the first synthesis of this type of hydrogenated aromatic macrocycle was achieved as early as 1958 by Linstead et al. (G. E. Ficken, R. P. Linstead, E. Stephen and M. Whalley, J. Chem. Soc., 1958, 3879), the development of modern synthetic strategies enables us to isolate stable forms of the hydrogenated TAP derivatives. Benzo-, 2,3-naphtho- and 1,2-naphtho-fused derivatives were synthesized extensively, and all structural isomers have been elucidated. The chemical structures have been characterized using a variety of techniques, including mass spectrometry, (1)H and (13)C NMR, X-ray crystallography and IR spectroscopy. The spectroscopic properties (e.g., electronic absorption, magnetic circular dichroism (MCD), and fluorescence) of these compounds differ significantly from those of the original TAPs, or phthalocyanines (Pcs), due to the symmetry-lowering effects of the core aromatic macrocycles. The experimentally observed properties have been rationalized on the basis of electrochemical studies and quantum chemical calculations. As an application of the TAC skeleton, the synthesis and electronic structures of tribenzo TAC (TBTAC)-C(60) conjugates, in which both components are covalently connected directly and thus show remarkable molecular orbital (MO) mixing between the constituting moieties, have also been reviewed.

Excited states and electronic spectra of extended tetraazaporphyrins

“…TAP is a compound that is derived by the introduction of nitrogen at the four mesopositions of the porphyrin basic skeleton ͑named as porphin͒. 1,2 What makes this compound so attractive is the high intensity of its Q-bands. The weak intensity of the Q-bands in unmodified porphin is explained by the cancellation of transition dipole moments between the transition from the highest occupied molecular orbital ͑HOMO͒ and the next-HOMO.…”

“…1,3 Consequently, the Q-bands of TAP in the visible region have high intensity, therefore TAP is regarded as an important fundamental material of dyes and pigments. 1,2 Phthalocyanines ͑Pc͒ are important derivatives of TAP that are widely used as chromophores and other materials in many fields.…”

“…14 Recently, a series of TAP congeners were synthesized and their UV-vis and magnetic circular dichroism ͑MCD͒ spectra were measured by Kobayashi's group. 2,[15][16][17][18] In particular they studied 16 the properties of TAP, Pc, naphthalocyanine ͑Nc͒, and anthracocyanine ͑Ac͒ ͑it is also called an-thracyanine͒; those compounds may be classified as a series of TAP derivatives in which -systems are extended by the sequential addition of fused benzene rings. They discussed the relations between properties and molecular sizes for freebase ͑metal free͒ and some metal compounds.…”

Influence of Exchange-Correlation Functional in the Calculations of Vertical Excitation Energies of Halogenated Copper Phthalocyanines using Time-Dependent Density Functional Theory (TD-DFT)

“…In addition, their absorption may be extended into the near infrared by suitable chemical engineering. [5][6][7][8][9][10][11][12][13][14] The properties and effects of these infrared-absorbing phthalocyanines are diverse and cover many important hi-tech applications, including photodynamic therapy, optical data storage, reverse saturable absorbers and solar screens. The majority of these applications exploit the unique optical properties of phthalocyanines, and thus a variety of spectroscopic techniques such as UV-vis spectroscopy, magnetic circular dichroism (MCD), and fluorescent as well as time-resolved fluorescent spectroscopy were used in the characterization of the excited states of phthalocyanines and their analogues.…”

Investigation of Tetramethyltribenzotetraazachlorin Association in Binary Mixtures of Polar Solvents and in Colloidal Solutions of Nonionic Surfactant

“…Тетраазахлорины являются гидрированными производными тетраазапорфина. В настоящий момент в литературе мало сведений об этих соединениях, [1][2][3][4][5] ввиду чего изучение их физико-химических свойств представляет большой интерес. С точки зрения практической значимости, тетраазахлорины, как и большинство аналогичных соединений, имеют большой потенциал для применения, например, в качестве сенсибилизаторов для фотодинамической терапии (ФДТ) онкологических заболеваний.…”