New developments as well as a historic overview on synthetic strategies for preparation of the rare-earth complexes with porphyrins, phthalocyanines, naphthalocyanines, tetraazaporphyrins, and related systems are discussed in detail with emphasis on selective synthetic pathways for preparation of single-, double, and triple-decker architectures. 6 IntroductionAfter their discovery almost 100 years ago, phthalocyanines (Pcs) were predominantly investigated because of their industrial applications as dyes, pigments, and catalysts [1][2][3].Similarly, historically, porphyrins (Pors) were intensively studied because of their importance in mimicking biologically relevant atom-and electron-transfer processes as well as light-harvesting mechanisms associated with living cells [4][5][6]. In addition, porphyrins, phthalocyanines, and their analogues were found to be useful in applications such as redox-driven fluorescence markers and biomarkers, light-harvesting antennas for organic photovoltaics and dye sensitized solar cells, charge carriers for copiers and printers, materials for molecular electronics, as well as redoxactive components in environmental, biological, and industrial sensors as well as active components in photodynamic therapy (PDT) and boron neutron therapy (BNT) of cancer [7][8][9][10][11][12][13][14][15][16][17][18][19].In their initial attempts, researchers focused on rich coordination, redox, and magnetic properties of the metal-free, main-group, and especially transition-metal porphyrinoids. It was soon realized, however, that the rare-earth ions can form unusual systems when coupled with the phthalocyanine ligand.The first rare-earth Pcs were reported by Russian scientists Kirin and Moskalev in 1965 [20]. Kirin and Moskalev also pointed out that because of the large ionic radii and high coordination numbers of the rare-earth ions, the formation of the double-decker rare-earth phthalocyanine compounds could be achieved under specific reaction conditions [20,21]. During the next 50 years, it was confirmed that rare-earth ions are capable of the formation of phthalocyanine single-, double, and triple-decker complexes and their analogues [22][23][24][25][26][27][28][29][30][31][32][33]. One of the interesting recent discoveries was the preparation and characterization of heteronuclear (rareearth / cadmium) multiple-decker complexes, which contain up to six Pc ligands [34][35][36][37][38][39][40][41][42].

Phthalocyanine compounds of novel type based on a bridged bis-ligand, denoted "intracavity" complexes, have been prepared. Complexation of clamshell ligand 1,1'-[benzene-1,2-diylbis(methanediyloxy)]bis[9(10),16(17),23(24)-tri-tert-butylphthalocyanine] ((clam,tBu)Pc(2)H(4), 1) with lanthanide(III) salts [Ln(acac)(3)]⋅n H(2)O (Ln = Eu, Dy, Lu; acetylacetonate) led to formation of double-deckers (clam,tBu)Pc(2)Ln (2 a-c). Formation of high molecular weight oligophthalocyanine complexes was demonstrated as well. The presence of an intramolecular covalent bridge affecting the relative arrangement of macrocycles was shown to result in specific physicochemical properties. A combination of UV/Vis/NIR and NMR spectroscopy, MALDI-TOF mass-spectrometry, cyclic voltammetry, and spectroelectrochemistry provided unambiguous characterization of the freshly prepared bis-phthalocyanines, and also revealed intrinsic peculiarities in the structure-property relationship, which were supported by theoretical calculations. Unexpected NMR activity of the paramagnetic dysprosium complex 2 b in the neutral π-radical form was observed and examined as well.

Methods for the selective synthesis of mono ( R PcLnOAc), di ( R Pc 2 Ln), and triphthalo cyanines ( R Pc 3 Ln 2 ) of rare earth metals (Ln = Lu, Er, Eu) from symmetrically substituted 2, 3,9,10,16,17,23,24 octaalkylphthalocyanines R PcH 2 (R = Et, Bu) were developed. The syn thesized complexes were characterized by NMR spectroscopy, mass spectrometry, and elec tronic absorption spectra. The conditions for 1 H NMR spectra recording were optimized. Regularities in changing the spectral properties of the synthesized compounds, depending on the lanthanide nature and the planarity of metal phthalocyanine complexes, were found.Rare earth metals (REM) have high coordination numbers and, hence, can form complexes of different compositions with phthalocyanines. 1-3 The unique physi cochemical properties of these complexes provide wide potentialities for their use in different fields of science and technology. 4-8 Accessibility of the phthalocyanine com plexes is a determining factor for practical use. However, their synthesis often produces a mixture of compounds, which impedes isolation and decreases the yields of target products. Therefore, the development of selective meth ods for the synthesis of lanthanide mono , di , and triphthalocyanines and studies of their structure and prop erties are of great significance.In this work, we studied conditions for the directed synthesis of several symmetric alkyl substituted mono , di , and triphthalocyanine complexes of REM and deter mined their spectral characteristics. The use of free ph thalocyanines as the starting compounds was shown to be more efficient than the use of the corresponding phthalo dinitriles, 9 because the reaction time is shortened sub stantially, isolation and purification become simpler, and, in most cases, the yield of target products increases. Results and DiscussionEthyl and butyl substituted phthalocyanines 1 and 2 were used as phthalocyanine ligands. Earlier, these com pounds were obtained in 21 and 38% yields, respec tively, by the reflux of diethyldiiminoisoindoline in N,N dimethylaminoethanol 10 or dibutylphthalodinitrile in n pentanol in the presence of metallic sodium. 11 It turned out that the reflux of solutions of 4,5 diethyl or 4,5 dibutylphthalodinitriles in isoamyl alcohol in the pres ence of lithium methoxide affords phthalocyanines 1 and 2 in 62-64% yields (Scheme 1). Scheme 1 R = Et (1), Bu (2) Reagents and conditions: i. C 5 H 11 i OH, MeOLi, 130 °С, 5-6 h.Monophthalocyanine complexes 3 and 4 were synthe sized under the conditions similar to the preparation of the tetracrown substituted lanthanide complexes. 12 The * Dedicated to Academician A. L. Buchachenko on the occa sion of his 70th birthday.

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Pc = 2-benzyloxy-9,10,16,17,23,24-hexa-n- Pc = 9,10,16,17,23,24-hexa-nbutyl-2-hydroxyphthalocyaninate) (2a, 2b), which are prom-

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A series of homoleptic bis{tetrakis(5,7-bis(4-tert-butylphenyl)-6H-1,4-diazepino)[2,3-b,g,l,q]porphyrazinato}lanthanide sandwich complexes [(tBuPh)DzPz]2Ln (Ln = Lu, Er, Dy, Eu, Nd, Ce, La) were prepared and their physicochemical properties were studied to gain insight into the nature of specific interactions in diazepinoporphyrazines. The effect of annulated diazepine moieties and the Ln ionic radius on the properties of the complexes was investigated in comparison with double-decker phthalocyanines. A combination of experimental and theoretical studies revealed the presence of two types of hydrogen bonding interactions in the metal-free porphyrazine and the corresponding sandwich complexes, namely, interligand C-H(ax)N(meso) hydrogen bonding and O-HN(Dz) ligand-water interaction. The interligand hydrogen bonding imparts high stability of the ligand dimer and the double-decker compounds in a reduced state. This work is the first comprehensive investigation into the fundamental understanding of the unusual properties of diazepine-containing macroheterocycles.

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