Yeni sübstitüe ftalosiyaninlerin sentezi ve özelliklerinin incelenmesi

Abstract

Koordinasyon kimyasının önemli bir bölümünü teşkil eden sübstitüe ve sübstitüe olmamış ftalosiyaninlerin yüksek ısı, ışık, asit ve bazlara karşı olan dayanıklıklan, ftalosiyaninlerin kullanım alanlarının gelişen teknolojiye paralel olarak oldukça geniş bir alana yayılmasına neden olmuştur. Ftalosiyaninlerin boya, optik ve elektriksel malzemeler olarak ticari kullanım alanlarının yanında yakıt pilleri, kimyasal sensörler, solar piller, fotodinamik kanser terapi gibi yüksek teknolojik kullanım alanlarına uygulanmaları da her geçen gün artmaktadır. Sübstitüe olmayan ftalosiyanin bileşikleri suda ve organik çözücülerde hiç çözünmediklerinden ftalosiyanin kimyasındaki araştırmaların önemli bir hedefi de çözünür ürünler elde etmektir. Bu çalışmada; N ve S atomlarını ihtiva eden iki farklı benzotiazolinin, metanolde aşın miktarda NaBHj ile indirgenmesi yoluyla elde edilen üç dişli tiol ligandlannın 1,2-dikloro- 4,5-disiyanobenzen ile reaksiyonu sonucunda iki yeni ftalonitril türevi sentezlenmiştir (4a, 4b). Bu ftalonitril türevleri ile periferal pozisyonlarda sübstitüe olmuş metalsiz ve metallo (M = Zn, Ni) ftalosiyaninler elde edilmiştir. 4a'nin Lutesyum tuzu ile siklotetramerizasyonu sonucu elde edilen Lutesyum bis(ftalosiyanin) kompleksi bilinen organik çözücülerin çoğunda kolaylıkla çözünmektedir. Elde edilen yeni maddelerin yapılan; Elementel analiz, İR, UV-VIS, NMR, ESR, kütle spektrumlan ve atomik absorbsiyon ölçümleri ile aydınlatılmıştır.

Coordination chemistry is the main branch of inorganic chemistry growing amazingly in the recent decades. The field of coordination chemistry of macrocyclic compounds has undergone spectacular growth since the beginning of this century. This growth has largely been due to the synthesis of a great number and variety of synthetic macrocycles which behave as coordinating ligands for metal ions. The development of the field of bioinorganic chemistry has also been an important factor in spurring the growth of interest in complexes of macrocyclic compounds since it has been recognized that many complexes containing synthetic macrocyclic ligands may serve as models for biologically important species which contain metal ions in macrocyclic ligand environments. The study of the properties and synthesis of macrocyclic compounds may have important consequences for biochemistry since many important compounds in living systems, such as chlorophyl, hemoglobin etc., contain macrocyclic porphyrin rings attached to metal atoms. The biosynthesis of these compounds probably in values some form of template synthesis. A group of related compounds, the phthalocyanines, are isoelectronic with porphyrins. They are interest not only as a model compounds for the biologically important porphyrins but also the commercially important intensively coloured metal complexes as dyes and pigments. A phthalocyanine is a synthetic macrocylic compound which was first reported in 1907 by Braun and Tcherniac, as a by-product of the preperation of o-cyanobenzamide from phthalamide and acetic anhydride at high temperature. The structure of this metal-free unsubstituted phthalocyanine was determined only about a quarter of century later by the comprehensive researches of Linstead and x-ray diffraction analyses of Robertson, while examining both metal-free phthalocyanine and metallophthalocyanines. Phthalocyanines and their metal complexes have been investigated for many years in great detail. While in former times phthalocyanines were mostly used as dyes and catalysts, lately phthalocyanine chemistry has been undergoing a revival, because phthalocyanines and many of its derivatives exhibit properties which are of interest for applications in material science. Many metallophthalocyanines can be easily synthesized in high yields and purity, and also exhibit a high thermal stability. Xlll As excellent blue and green dyestuffs, phthalocyanines are an important article of commerce used in inks (ballpoint pens), dyestufis for textiles and colouring for plastic and metal surfaces, and are produced at over 50 000 tons per year. Phthalocyanines and structurally related compounds are of interest in non linear optics, as liquid crystals, as Langmuir-Blodgett (LB) films, in optical data storage, as electrochromic substances, as low dimensional metals, in rectifying devices, as gas sensors, as photosensitizers and as carrier generation materials in NIR. The substituted derivates of phthalocyanines function as active components in various processes driven by visible light: photoredox reactions and photooxidations in solution, activity in the theraphy of cancer, photoelectrochemical cells, photovoltaic cells and electrophotographic applications. An essential shortcoming of the phthalocyanines and structural analogues remained their low solubility in organic solvents which made difficult their application in solutions. The introduction into benzenic rings of the phthalocyanine molecule of voluminous substituents results in weaking of intermolecular interaction in the crystalline state and subsequently in a drastic increase of solubility in organic solvent, especially nonpolar ones. Moreover, the introduction of various substituents, such as amino, phenylthio groups, into benzenic rings turned out to be a powerful means of modifying the chemical and physical properties of the phthalocyanines. Much attention has been paid to bis(phthalocyaninato) lanthanide complexes, especially lutetium complexes, [LnPc2] (Pc=phthalocyaninato dianion), because they are considered as the most promising electrochromic display materials, materials for molecular semiconductors, and attractive canditates for nonlinear optical applications. Considerable efforts have been made to investigate their spectral, electrochromic, electrochemical,magnetic and structural properties. Most of the interesting characteristics of the bis(phthalocyaninato)lanthanide complexes from their sandwich-type sturcture and the interplanar interaction between the 7i-electron system of the two Pc rings. Several structures of lutetium complexes have extensively been reported. From these structures, it is generally accepted that lutetium ion occupies the central position with eight coordinated nitrogen atoms of the two phthalocyaninato moieties, which are parallel and are in a staggered conformation relative to each other (approximately 45°). Unlike diphthalocyanine of rare-earth elements (REE) which have been objects of extensive investigation because of their electrochromic properties, REE mono- phthalocyanine have scarcely been studied at all. Unlike lutetium diphthalocyanine, which is a stable free radical of the type LuPc2, the monomelic phthalocyanines are diamagnetic over a wide range of temperatures. In the electrochemical reduction of the radical cations, there occurs the quantitative reduction of the original monophthalocyanine. This suggests the possibility of their use, together with diphthalocyanines as electrochromic compounds. Pure substituted phthalocyanines are prepared by cyclotetramerization of substituted 1,2- dicyanobenzenes or 1,3-diimino-lH-isoindoles, If monosubstituted 1,2-dicyanobenzenes are employed, tetrasubstituted phthalocyanines with the disadvantage of a mixture of place isomers are obtained, 4,5-Disubstituted derivatives as starting materials lead to 2,3,9,10,16,17,23,24-identically substituted phthalocyanines. The two substituents of the 1,2-dicyanobenzenes had to be introduced at a precursor, and a longer preparative route is necessary for 2,3,9,10,16,17,23,24-octasubstituted phthalocyanines. XIV A diagnostic feature of the phthalocyanine formation from the cyano derivatives is the disapperance of sharp intense ON vibration bands of the reactants in the IR spectrum. The NH groups in the inner core of the 5a, 5b give an absorbtion at 3290 cm"1. The XH- NMR spectra of the new metal-free and Zn(U) phthalocyanines in deutored DMSO give rather broad peaks both as a concequence of aggregation of pc units and the presence of isomers resulting from the position of substituents with respect to each other. Also, the broad absorption around - 4.29 ppm in 5a, 5b can be easily ascribed to inner core protons while it disappears by D20 exchange. These protons could not be observed for 6a, 6b. Chemical shifts due to the alkyl, aromatic and secondary amine group protons are the dominating signal in the spectra 5a, 5b, 6a, 6b. The visible absorbtion spectra of 6a, 6b in DMF shows the intense Q band absorption at 699 ran. There is a shoulder at slightly higher energy side for both products. The longer wavelength encountered for 5a, 5b is especially noteworthy to denote the shift of this intense band to near-IR region as a result of S-substitution. The lower solubility of 7a, 7b meant their spectra could be obtained only in concentrated sulphuric acid. The electronic spectra of 7a, 7b could show the solvent and S-substitution effects with the shift of lower- energy apsorption to the near-IR region (kaax> 800 nm). In the last of the study, lutetium bis(phthalocyanine), [L11PC2], 8a was synthesized from reaction of dinitrile derivative 4a with Lu(OAC)3. 3H20, l,8-diazabicyclo[5,4,0]undec-7-ene(DBU) in 1-hexanol at reflux temperature for 20 h (Scheme 2). Purification was achieved by column chromatography (silica gel). The most obvious feature of complex 8a is their high solubility in common organic solvents, e.g.chloroform, dichloromethane, THF, acetone, DMF and DMSO, etc. The IR and 'H-NMR spectra are consistent with the proposed structure. In the IR spectrum of 8a, the characteristic band of LuPc2 at 1472 cm"1 is observed. The band observed at 820 cm"1 for the 8a is usually attributed to the central ion-ligand vibration. In the ^-NMR spectra of 8a, aromatic protons are not observed distincly in the neutral form, probably because of their proximity to the paramagnetic center. However a very broad signals between 6.97-8.25 nm could be attributed to the pyridine groups. These results confirm that the paramagnetism of LuPc2 strongly perturbs the proton signals in the aromatic region. The electronic spectra of 8a contained a Q band at 698 nm, a Soret band 329 nm and a typical radical phthalocyanine anion band as a shoulder in the 400-500 nm region. Electron spin resonance data for LuPc2 confirmed the free-radical nature of the green LuPc2 complex. The ESR spectrum of 8a, which shows a strong signal at g=2.00373 confirms the presence of an unpaired spin and is consistent with the occurrence of a phthalocyanine radical. XVI 1 N =?