Difenilmetilamin'den yeni ftalosiyanin, vic-Dioksim ve komplekslerinin sentezi

Abstract

The beginning of coordination chemistry is dated to 1893 when Alfred Werner and S.Mads Jorgensen synthesized and identified the first coordination compound. The tenets of the Werner's theory have not been discarced, but they have been refined and greatly extented. For example, early workers considered coordination compounds of only a few metals (e.g. Pt, Co, Cr) and coordination numbers of four and six. During the following years, more researchers on coordination compounds have been concerned with nearly all the metals in the periodic table, with all coordination numbers from two to twelve and in many oxidation states. The development of the crystal field and molecular orbital theories have greatly aided in the understanding of new structures. Werner's theory said that all six-coordinate complexes are octahedral. That we know, the most of them are octahedral, but there are some that are triangular prismatic and a few that are pentagonal pyramidal. Metal ions are influenced ligand reactions by several ways. These effects can result in increased acidity of the ligand either directly at the donor atom or via conjugation to another part of the ligand. The most reactions of coordinated ligands occur in complexes of transition metals, because of the inherent stability of these complexes and also the relatively high charge on the metal. The phthalocyanines constitute a long established class of commercially important dyes and pigments. However, there is increasing interest in their redox, electrical, optoelectronic and photophysical properties for applications within a variety of devices. Therefore, this has provided impetus for the design and synthesis of new derivatives showing specialised behaviour or properties. Dye molecules covalently attached or adsorbed on to semiconductor electrodes may sensitize the electrode to visible light. Thus it may be possible to produce photocurrents and photovoltages corresponding to longer wavelengths of light than would correlate with the semiconductor band gap. Metallophthalocyanines are a very attractive choice of dye since they are stable and the chromophores absorb strongly in the solar spectrum. Also a wide variety of metal phthalocyanines are known; thus a wide range of redox potentials is available, and indeed some are semiconductors in their own right. During the last decade, research on the applications, syntheses and evaluation of various types of phthalocyanines have reached a new dimension. Octa-substituted phthalocyanines can be deposited as thin films by the Langmuir-Blodgett (LB) techniques and the use of these films as the chemically active component in chemical sensors. The other hand tetra-and symmetrically octa-substituted derivatives are useful compounds in nonlinear optics as LB films as well as organic semiconductors. They also have liquid-crystalline phases due to long peripheral alkyl chains. The conductive properties of discotic liquid-crystalline pthalocyanines have been investigated by several research groups. Phthalocyanine is well known as a disk-like molecule and forms a one-dimensional columnar structure in condensed phases. Our research group and co-worker J. Simon synthesized a crown-ether substituted phthalocyanine shows an original mesophase. with a square lattice. Other phthalocyanine derivatives exhibit different mesophases. For example; A chiral-chain- substituted phthalocyanine shows a discotic-cholesteric mesophase, a 2-ethyl- hexyloxy-substituted phthalocyanine exhibits both a discotic tetragonal disordered columnar phase and a discotic nematic phase. A polymeric phthalocyanine and a strip-like dimeric phthalocyanine derivative exhibit a lamellar phase. Thus various mesophases appear corresponding to the different peripheral substituents. Phthalocyanine derivatives offer a very wide choice of molecular physicochemical properties by changing the type of metal complexes in addition their nature of the substituents. Small divalent ion complexes of unsubstituted phthalocyanine [Cu(II), Ni(II), Zn(II),...] are in most cases of D4h symmetry. The solubility is an important property in phthalocyanine chemistry and application areas. It is quite clear that the some phtalocyanines show better solubility than the others. In many studies of solubility of phthalocyanines, an important point that might be of prime interest are the properties of the substituents in the structure and the positions of the substituents relative to the phthalocyanine core and possibly relative to one another. Many researchers have been interested in the solubility and selectivity of several macrocyclic donor groups towards metal ions by attaching them as peripheral substituents onto phthalocyanines. Most of these macrocyclic donors, such as crown ethers, tetraaza, diazadioxa and tetrathia, provide to bind the transition metal ions. The aim of this study is to synthesize a new phthalocyanine and a vic-dioxime containing bulky diphenyl-methyl groups starting with diphenylmethylamine. As a first step, diphenylmethylamine was synthesized from benzophenone according to given literatures. Because of its high tendency to reactivity, diphenylmethylamine was directly reacted with l,2-dibromo-4,5-bis(bromomethyl)benzene under K2CO3 base condition in dimethylformamide as solvent. The amounts of the reagents were determined in 2/1 molar ratio (2 mol is belong to amine). We obtained a new compound, but (1) was rather different than we expected. The condensation reaction had taken place in 1/1 molar ratio between the two reagents and binded forming five membered a new ring. xi On the other hand, when dealing with the reaction to obtain (1), one have greatly aided by the spectral data that could be determined for the reactants and the products. Phthalocyanine formation is accomplished either directly by the reaction of the dibromo derivative with CuCN in a suitable solvent, or by converting into the dicyano-derivative according to the Rosenmund von Braun Reaction under mild conditions and then using this compound to prepare other metallophthalocyanines. The new dibromo compound could not be converted to the phthalocyanine under the conditions used, such as, DMF, pyridine, TMU, quinoline as solvent in a sealed tube. At the same time we have striven for occurring a dicyano-derivative by the Rosenmund von Braun Reaction. Unfortunately all trials were negatively ended and (1) decomposed (Scheme 1). X=Br x > Pc - *CN Scheme 1. Synthesis of (4,5-dibromo-2,7-dihydro-l-diphenylmethyl) indoline(l). The dibromo compound has good solubility in organic solvents such as chloroform, dichlomethane, carbontetrachloride, benzene and it is very stable compound but nonreactive. We can explain the nonreactivity of (1) because of occurring the five- membered ring and its steric strain. Therefore, the study was redesigned (Scheme 2) and diphenylmethylamine was tosylated with p-toluensulphonylchloride in pyridine at 0°C to protect it during the subsequent reactions. Thus, we obtained diphenylmethyl-p-toluen sulphonyl-amine as the compound (2). Under weak potassium carbonate base conditions, 1,2-dibromo- 4,5-bis(bromomethyl)benzene was reacted with (2) to form the l,2-dibromo-4,5- bis(N-p-tolylsulphonyldiphenylmethylaminomethyl)benzene in DMF. The cyclotetramerization of (3) with copper(I)cyanide gave the copper phthalocyanine (4) in DMF. XII x^ \^ (4) Scheme 2. The general route of the synthesis of new phthalocyanine. xui The IR spectrum of (2) exhibits characteristic frequencies at 3250 cm"1 (NH), 3020 cm"1 (CH arom.), 2980-2840crrr1 (CH aliph.), 1300 and 1180 cm"1 (S02). The IR spectrum öf (3) clearly indicates the absence of (NH) group by the intense characteristic streching bands at 3250 cm"1, but a new peak shows the (C-Br) vibration at 580 cm"1. Comparison of the IR spectral data of (3) and (4) indicates the convertion of the dibromo-groups into dicyano-derivatives by the appearance of a new (C=N) band at 2250 cm"1. The phthalocyanines show typical electronic spectra with two strong absorption regions, the first appears in the UV region at about 300-350 nm (B band) and the other in the visible region at 600-700 nm (Q band). The characteristic Q band transition of Cu(Pc) with D^ symmetry has observed as a singlet at 688 nm. In extremely dilute solutions (ca: 10"6 mol) phthalocyanine molecules are monomeric structure. Gradual increases in concentration result in a lowering in the intensity of the Q band at 688 nm together with a slight increase in the absorption at 655 nm denoting the formation of aggregated species. In recent years oximes have found increasing research interest. The high quality which has been attained in the manufacture of oxime products is due to the remarkable advances in oxime chemistry and its applications. The most significant early discovery in the chemistry of metal oximates was the reaction between nickel (II) salts and dimethylglyoxime, which is the best known example of a vicinal dioxime (abbreviated as vic-dioxime). The discoverer Tschugaeff correctly identified the bidendate nature of vic-dioximes. However, the chelate ring size remained uncertain and went through the incorrect seven-and six-membered formulations before the correct five-membered ring was fully established. Interesting historical accounts of oximes are well documented. Active interest has continued on various facets of metal oximate chemistry as evinced by publication of a number of review articles, it may, however, be mentioned that the last two mainly deal with 0-bonded oximate derivatives of organometallic moieties and metals. The important features, apart from N4 planar binding, are the strong 0...H...0 hydrogen bondings and the stacking of the planar units parallel to each other in the crystal, in the cases of Ni(II) and Pd(II) complexes in general. The nature of metal- metal interactions in such chains has been reviewed recently. The aim of this second study is to synthesize a new ligand containing bulky diphenyl- methyl groups which will be suitable to form soluble vic-dioxime and its metal complexes. First of all, diphenylmethylamine was synthesized starting with benzophenone as described in the first part. l,2-bis(diphenylmethylamino) glyoxime was synthesized from the reaction of diphenylmethylamine with dicyan-di-N-oxide. The transition metal complexes that is obtained from (5) were isolated and characterized (Scheme 3). XIV HN-_^ NOH +C = NO X^NOH Scheme 3. The synthesis of l,2-bis(diphenylmethylamino)glyoxime, (5) In the study of IR spectrum it has been observed that OH stretching vibration forms at 3380cm"1, (N-H), (ON) and (N-O) stretching vibrations are at 3250, 1640 and 950 cm-1 respectively. In the 'H-NMR spectrum of oxime the (OH) and (NH) protons seem as two singlets at 10.1 and 6.1 ppm. These singlets disappear by deuterium exchange. A single chemical shift for (OH) proton indicate that the oxime group is in the anti-form. Also the spectrum shows that aliphatic (CH) group is at 5.7 ppm and aromatic protons are at 7.2 ppm as multiple!. The reaction of (5) with Ni(H), Cu(H), Pd(II) and U02(VI) salts give mono-and di- nuclear complexes at 1/2 and 1/1 metal/ligand ratios (Scheme 4). The mono-nuclear complexes of Ni(H), Cu(II), Pd(II) have metal/ligand ratios of 1/2 according to the elemental analysis. The IR spectrum of the (6), (7) and (8) exhibit (C=N) absorptions at 1580 cm"l due to the complex formation. The lowering of this vibration for oximes implies that the ligand is NN1-coordinated to metal (II). The new band at 1750 cm"1 shows bending vibration of intra-molecular hydrogen bridged (0...H-O) groups. The Nİ(II) complex has square planar structure and is diamagnetic. The İH-NMR spectrum has also been confirmed the structure. The chemical shifts have observed at lower field because of complex formation. xv M Ni(ll), (6) Cu(ll), (7) Pd(!l), (8) Ö H O Scheme 4. Mono- and di-nuclear complexes Di-nuclear UO2CVI) complex, (9) was prepared from the uranylacetate salt with the oxime in ethanol. The elemental analysis of the (10) indicated that metal/ligand ratio is 1/1. The IR spectrum is also consistent with dimeric structure. A strong band around 900 cm~l is the characteristic frequency for (0=U=0) vibrations. This di-nuclear complex has shown similarities in the spectral data with the dimethylglyoximatecobalt analogs. In the UV-VIS spectra charge-transfer band have been observed around 400 nm. In this second part of the study, we obtained a new compound while we were trying to form the Cu(II) complex as a solid compound by precipitation. This coincidental compound (10), has no any metal but it contains two five-membered ring binded XVI each other. We decided that (10) occurred by means of template effect of Cu(II) ion. The Cu(II) ion served as a template on which the oxadiazole rings are assembled, and which is subsequently eliminated (Scheme 5.). The structure of oximes was actively debated for the first three decades of the 20th century, and it is only with the advent of physical methods that the matter has at last been resolved. The isomeric nitrone and oxaziridine structures, as well as vinyl hydroxylamine tautomer, were for a time considered to offer explanations for the existence of the various isomeric forms encountered with some oximes and their derivatives. Nitrones can undergo 1,3-cycloaddition with C=C or C=N unsaturation, membered rings, isoxazolidines or 1,2,4-oxadiazolidines, are formed. five Nitrons are reasonably stable substances when derived from aromatic ketones or aldehydes. Nitrones having a benzhydryl or triphenylmethyl group on the nitrogen rearrange on heating just as do similarly constituted amine oxides, to form the o- substituted isomers. The preferred configuration (thermodynamically more stable) of ketoximes is determined by both steric and electronic factors in saturated, aliphatic oximes, where the steric factor is the only significant one, interconversion is too rapid to permit isolation, but it is assumed that the more stable form is that with hydroxyl syn- to the least bulky group. The structure of 3,3'-bis(5-diphenyl-l,2,4-oxadiazole) has confirmed by elemental analysis, IR, ^-NMR, 13C-NMR and mass spectrographs. /\ \^ HN NH \^ Scheme 5. 3,3'-bis(5-diphenyl-l,2,4-oxadiazole).