Handbook of Polymer Synthesis Second Edition Episode 11 pptx

11 Metal-Containing Macromolecules Dieter Wo ¨ hrle University of Bremen, Bremen, Germany I. FUNDAMENTALS ABOUT METAL-CONTAINING MACROMOLECULES A. Classification In metal-containing macromolecules or macromolecular metal complexes (MMC) (article in the previous edition of the Handbook see [1]) suit able compounds are combined to materials with new unusual properties: organic or inorganic macromolecules with metal ions, complexes, chelates or also metal clusters. Thes e combinations result in new materials with high activities and specific selectivities in different functions. This article concentrates on synthetic aspects of artificial metal-containing macromolecules. Properties are shortly mentioned, and one has to look for more details in the cited lite ratures. In order to understand what kind of properties are realized in metal-containing macromolecules, in a first view functions of comparable natural systems (a short overview is given below) has to be considered:  metallo-enzymes for catalysis,  hemoglobin, myoglobin for gas transport,  cofactors for electron-interaction,  apparatus of photosynthesis for energy conversion,  metallo-proteins and related systems for various functions. For meta l-containing polymers it is important to understand also their molecular arrangements: primary structure (composition of a MMC); secondary structure (steric orientation of a MMC unit); tertiary structure (orientation of the whole MMC); quarternary structure (interaction of different MMCs). The more detailed knowledge about biological macromolecular metal complexes led in the recent years to an intensified research. The activities in this field are parts of IUPAC conferences on Macromolecule- Metal Complexes (MMC I–VII [2]), and are summarized in some monographs and several reviews [3–45]. Various combinations of macromolecules and metal components such as metal ions, metal complexes and metal chelates exist. The side of the macromolecule considers mainly organic polymers, for example, based on polystyrene, polyethyleneimine, polymethacrylic acid, polyvinylpyridines, polyvinylimidazoles and others. The main chain of these polymers can be linear or crosslinked. In several cases a metal is part of the polymer chain leading to new structural units. Inorganic macromolecules like silica, different kinds Copyright 2005 by Marcel Dekker. All Rights Reserved. of sol-gel materials or molecular sieves can be included also if these macromolecules are modified in such a way to carry as active part one metal component in a specific kind of interaction with the carrier. A classification of metal-containing macrom olecules is as follows. Type I: A metal ion, a metal complex or metal chelate is connected with a linear or crosslinked macromolecule by covalent, coordinative, chelate, ionic or p -type bonds (Figure 1). This type I is realized by binding of the metal part at a linear, crosslinked polymer or at the outer or interior surface of an inorganic support. Another possibility uses the polymerization or copolymerization of metal containing monomers. Type II: The ligand of a metal complex or metal chelate is part of a linear or crosslinked macromolecule (Figure 2). Either a multifunctional ligand/metal complex or a multifunctional ligand metal complex precursor are converted in polyreactions to type II macromolecular metal complexes. Type III: The metal is part of a polymer chain or network. This type considers homochain or heterochain polymers with covalent bonds to the metal, coordinative bonds between metal ions and a polyfunctional ligand (coordination polymers), p-complexes in the main chain with a metal, cofacially stacked polymer metal complexes and different types (polycatenanes, polyrotaxanes, dendrimers with metals) (Figure 3). Type IV: This type is concerned with the physical incorporation of different kinds of metal complexes or metal chelates in linear or crosslinked organic or inorganic macromolecules. The formation and stabilization of metal and semicon ductor cluster will be not considered in this review (Figure 4). Because in most cases no clear IUPAC nomenclature exists for metal-containing macromolecules or macromolecular metal complexes, it is not possible to obtain by a Chemical Abstract literature search a detailed information on them. One ha s to look for each individual metal, metal ion, metal complex, metal chelate, ligand or also polymer. For type I usuall y rational nomenclature is used (for example: cobalt(II) complex with/ of poly(4-vinylpyridine) or 2,9,16,23-tetrakis(4-hydroxyphenyl)phthalocyanine zinc(II) Figure 1 Type I: Metal ions, complexes, chelates at macromolecules. Figure 2 Type II: Ligand of metal complexes, chelates as part of linear or crosslinked macromolecules. Copyright 2005 by Marcel Dekker. All Rights Reserved. complex covalently bound at poly(methacrylic acid). In the case of type II often the metal complex in combination with the term poly is used, e.g., poly(metal phthalocyanines) from 1,2,4,5-tetracyanbenzene. IUPAC nomenclature of type III are described as ‘regular single-strand’ and ‘quasi single stra nd’ inorganic and coordination polymers in [46]. The detailed name of the metal complex in polymers or inorganic macromolecules are a common description for type IV. B. Kinetical, Thermodynamical, and Analytical Aspects of Macromolecular Metal Complex Formation As in low molecular weight metal complexes, the process of complex formation of metal ion binding in macromolecular metal complexes is accompanied by numerous complicated factors like ion exchange equilibrium, ligand conformational changes, influence in the change of the electrostatic potential, etc. Kind and strength of the formed bonds between metal and ligand depend on the ionisation potential of the metal ion , its electron affinity and the donor properties of the ligand groups. For macro molecular metal complexes either in solution or in the solid state various secondary binding forces are of importance and determine, besides the covalent and ionic bonds, secondary, tertiary and quaternary structures. In addition, specific polymer parameters like degree of crosslinking, distribution of ligands, and, in the case of insoluble polymers, the topography of a macroligand or protecting high molecular weight surrounding must be considered. Many unsolved problems exist in the field of physical chemistry of complex formation, secondary binding forces, composition and reactivity of metal-containing polymers due to their manifold structures. The present situation is best described in [3]. Different models were used to describe the interaction of metal ions with macroligands of type I and some type II complexes. In one considered model for linea r Figure 4 Type IV: Physical incorporation of metal complexes, chelates. Figure 3 Type III: Metals as part of a linear chain or network. Copyright 2005 by Marcel Dekker. All Rights Reserved. macroligands the polymer ligand L is the central particle, and the metal ion/complex is added in a stepwise manner. In this case the equilibrium constant will not depend on the molecular weight of the macroligand. A second model based on the metal ion M as central particle is described by the Flory concept of infinitely large chains with the reactivity of binding centers independent on their position in the polymer [3]. Another approach calculated the sequence equilibrium which means equilibrium constans for the metal ion binding at different positions at the macroligand ([47,48] and literature cited therein). The equilibrium is usually described by the equilibrium constant " KK of a macroligand L-containing metal ion (M þ ) as complexed repeating units [equations (1) and (2)] [3,47–51] (Cp and Cs: initial concentrations of polymer (expressed in repeating units) and metal salt; a: fraction of metal ion/complex not complexed by the polymer). ð1Þ ð2Þ The right side of equation (3) is not totally correct because the equilibrium concentration of the macroligand [–L n –] 6¼ (Cp/n-Cs(1  a)) [47]. The reason is that a sequence of n þ 1 vacant repeating units can consist of different but overlapping neighbor sequences of polymer units. Different length between not complexed sequences exists which influence each other and results in different equilibrium constants k 1 , k 2 , k 3 k x [equations (3)–(5)]. ð3Þ ð4Þ ð5Þ A theoretical model allows to determine k 1 and k 2 on the basis of a numeral fit a ¼ f(n, [L] 0 ,[M þ ] 0 , k 1 , k 2 )with[L] 0 ,[M þ ] 0 . The validity of the model was tested for the interaction of Na þ (as Na þ B[C 6 H 5 ] 4  ) with poly(oxyethylene) in methanol. The best fit between measured and calculated values are found for n ¼ 1withk 1 ¼ 1.9 mol 1 L and k 1 /k 2 ¼ 3.5. Cooperative effects with changes in polymer chain conformati on under complex formation must be considered in addition [3]. Bending of a polymer chain by coordination of different ligand groups of one polymer chain leads to an increase of macroligand reactivity (increase of formation constant in comparison to separated, e.g., low molecular weight ligand enters). This was discussed for metal binding at poly(oxyethylene) and poly(4-vinylpyridine) [52,53]. Copyright 2005 by Marcel Dekker. All Rights Reserved. In the case of crosslinked macroligands electrostatic factors significantly influence the co mposition, structure and stability of a metal complex. Metal ion/complex binding can be described as mentioned before. In heterogeneous systems, when the ligand groups are mainly arranged on a surface with zero concentration in solution, diffusion and topological restrictions must be considered. At low binding center concentrations a Langmuir equation is valid for binding of a metal ion/complex [equation (6)] [3,53] ( f: maximum binding of metal ion/complex by a macroligand). ½M þ  ½M bound ¼ 1 " KK þ ½M f max ð6Þ One example is the binding of Cu 2þ by a crosslinked polymer containing bis (carboxymethyl)amino ligand groups with " KK ¼ 3:5  10 3 L=mol and f max ¼ 0.075 mmol/g [54]. For a non-porous solid matrix containing ligands grafted on a surface the stability of the complex is independent of the degree of surface coverage as shown for CuCl 2 or PtCl 2 on Aerosil from acetonitrile [55]. The formation of type II metal-c ontaining macromolecules obtained by the reaction of bi/multifunctional low molecular weight metal complexes with another bi/multi- functional ligand can be evaluated by usual rate constants, equilibrium and kinetics as known for polycondensation or polyaddition reactions in macromolecular chemistry. Increasing insolubility results easily in chain termination and formation oligomers. The therm al polycondensation of dihydroxy(metallo)phthalocyanines to cofacially stacked polymer in the solid state as example of a type III polymers [equation (7)] is topotactic and under topochemical control, which means that well-defined intermolecular distances and interactions in the lattice control the reaction [56]. Following a kinetic study the fraction of unreacted –OH end groups X over time does not obey a first order kinetics (X ¼ exp( k 2 t 2 ), M ¼ Si, Ge, Sn; n ¼ 50–200). nHOMðPcÞOH ! HOð MðPcÞOÞ n H þ n1H 2 O ð7Þ Besides the kinetic also the thermodynamic during the formation of MMCs is complicated. Changes of the conformation of macromolecules, for example, the chain flexibility, the electrical charges and others influence the thermodynamic parameters such as ÁS in the formation of different types of metal-containing macromolecules [3,57]. The general expression for the reaction is shown in equation (8). ÁG ¼RT ln " KK ¼ ÁH  TÁS ð8Þ For the formation of a low molecular weight chelate the so-called chelated effect in dependence on kind of solvent interaction is in the order of  5to 20 kJ/mol mainly determined by entropic terms). The polymer chelate effect for type I polymers is more complicated and includes besides the above-mentioned parameters also local, molecular and supramolecular organizations of macromolecules [6,58]. With a low degree of chelation ÁH for macroligands and low molecular weight ligands in the interaction with metal ions are comparable, but ÁS is different (polymer chelate effect) as it was shown for the reaction of amines with Cu 2þ [59]. For concentrated solutions as well as suspensions, interactions such as intermolecular or supramolecular organizations must be considered and are determined by entropic terms. A more detailed discussion are included in [3]. Copyright 2005 by Marcel Dekker. All Rights Reserved. By intermolecular interactions between the macroligand and the metal ion/complex the temperatur e of ligand $ gel formation, T tr , is influenced by the ultimate polymer concentration L ul [60]. Above L ul the T tr is independent on the concentration of the polymer and its molecular weight. In the case of Fe 3þ -polyhydroxamine acid, infinite networks are formed when the probability of intermolecular metal binding is above 50% [6,61]. Type II and III metal-containing macromolecules often form insoluble, more or less crystalline products. Therefore entropic terms going from solution to a crystalline or amorphous precipitate must be considered. Entropic terms are also important for the stabilization of metal clusters or metal complexes/chelates in a high molecular weight surrounding (type IV compounds). During formation of MMCs various thermodynamic side effects driven by a thermodynamically favoured terms can occur. This includes conformational changes, modification of functional groups and also macrochain breakage. Examples of conformational changes are: chain transformation in poly(oxyethylene)-transition metal complexes [61,62], double helix model of poly(oxyethylene)-alkali metal ion complexes [63], conformational modifications of poly(2-vinylpyridine) or poly(amidoamines) during complex formation [64,65], and others. Important to mention here is that chain destruction can occur in type I polymers during their formation [3,66,67]. A detailed analysis is the fundamental prerequisite to correlate structure and properties of the new materials. After preparation and isolation of a metal-containing macromolecule at first one has to analyze on the composition of the new material (primary structure). Well-known analytical methods can be used. For soluble compounds usual methods of molecular weight determination can be applied. Microcalorimetric studies allow to measure the enthalpy of formation of a metal-containing macromolecule. In some cases by potentiometric or conductometric measurements complex formation constants can be determined [3,6]. More complicated are the investigation of the secondary, tertiary and quaternary structure of metal-containing macromolecules either in solution or in the solid state. Each method (IR, UV/VIS/NIR, Raman, acoustic, dielectric loss, several methods of x-ray and Mo ¨ ssbauer, ESCA, XAFS, various magnetochemical, ESR techniques, solution/solid NMR, etc.) provides some information on type I–IV compounds. In nearly every case some special analytical investigations must be carried out. This is demonstrated for polyphthalocyanines of type II structure. These polymers are obtained by two-dimensional layer growth from various tetracarbonitriles as bifunctional monomers. A polymeric phthalocyanine has in an ideal case a regular planar structure which can be treated in a two-dimensional Cartesian coordinate system allowing positive integers (propagation directions of the polymers are denoted by the letters x and y) [68]. A model describing the structural features such as degree of polymerization, size and shape of polymeric phthalocyanines has been discussed. Equation (9) correlates now the number of macrocycles n (degree of polymerization) with the number of bridged monomers b and the number of end monomers e. n ¼ b=2 þ e=4 ð9Þ Evaluation of some data (determination of number of nitrile end groups and groups of bridged monomers by qua ntitative IR spectra) leads, in dependence on the kind of tetracarbonitrile and reaction conditions, to values of x ¼ 4–1 and y ¼ 1– 1. In addition Copyright 2005 by Marcel Dekker. All Rights Reserved. it was shown that the unique structure of polymeric phthalocyanines exhibits fractal properties. They have a regular structure and four fractal dimensions for every size/shape/ dilation combination [68]. This important mathematical model can serve as polymer model for discussing basic fractals. Cofacial stacked polymeric phthalocyanines contain- ing four substituents and their possible isomers in such a stacking were also treated mathematically [69]. II. METAL-CONTAINING MACROMOLECULES IN BIOLOGICAL SYSTEMS A. Metal Complexes in Living Systems The range of metals used by biological systems is very large, reaching from the alkaline to the transition metals [14–19]. They play an essential role in living systems, both in growth and metabolism. Some metals such as Na, K, Ca, Mg, Fe, Zn are necessary in g quantities. Other trace elements such as Cu, Mn, Mo, Co, V, W, Ni are essential beneficial nutrients at low levels but metabolic poisons at high levels. Some meta l ions such as Pb, Cd are called ‘detrimental metal ions’ because they are toxic and impair the regular course at life functions at all concentrations. Metal ions such as Ca, Mg, Na, K, Mn exhibit more ionic or coordinative interactions whereas Pt, Hg, Cd, Pb are going more for the covalent bonds, and Ni, Cu, Zn have to be considered as inter mediates. In biological systems metal ions can coordinate to a variety of biomolecules such as (Table 1):  proteins at the (C¼O)- or (N–H)-bonds and especially, at N, O, S-donor atoms of side chains; Table 1 Important bioligand groups and their coordination to metals in natural systems (after Reedijk in [3]) Ligand group Metal Substance in which detect or proven ¼O Fe P-450 enzymes –OH Fe, Zn Carbonic anhydrase H 2 O Fe, Zn, Ca Many proteins; additional ligands O 2 /O 2 2 Fe, Cu Hemoglobin, hemocyanin, hemerythrin O 2  Cu, Fe Superoxide dismutase –OOH  Fe Haemerythrin Tyrosine Fe Oxidases Glutamase (and Asp) Fe Hemerythrin, ribonucleotide reductase OPO 2 R Ca, Mg Nucleic acids; ATP NO 3  ,SO 3 2 Mo Several reductases –Cl  Mn Mn cluster in photosynthesis –S 2 Fe, Mo Ferredoxin; nitrogenase –SR  (cysteine) Fe, Cu Ferrodoxin, plastocyanin, P-450, azurins Me–S–R (methionine) Cu, Fe Plastocyanin, cytochromes, azurins Imidazole Cu, Zn, Fe, Mn Plastocyanin, insulin Benzimidazole Co Vitamin B-12 (N<)  (peptide) Cu Albumin Tetrapyrroles Fe, Co, Ni, Mg Prosthetic groups, hemoglobin CO Fe Toxic for myoglobin; cytochrome oxidase (CH 2 –R)  Co Vitamin B-12 Copyright 2005 by Marcel Dekker. All Rights Reserved.  nucleic acids at basic N-donor atoms or at phosphate groups;  carbohydrates and lipids at (C–O)- and (P–O)-groups;  in solid bones, teeth, kidney stones. Metal or metal compound clusters are found, for example, in the respiratory chain (Fe–S clusters) or in the photosynthesis apparatus (Mn clusters). B. Metal Complexes at Natural Polymer A bridge betw een natural and artificial macromolecular metal complexes is the interaction of metal ions/complexes with peptides/proteins [70], nucleic acids/DNA [71,72], enzymes [73], steroids [74], carbohydrates [75]. Biometal-organic chemistry concentrates on such complexes [15]. The reason for the increasing interest in this field lays in medical applications of metal complexes [16,76] (cancer, photodynamic therapy of cancer – immuno-assays, fluorescence markers, enantioselective catalysis, template orientated synthesis of peptides) as exemplarily shown below. Stable metal complexes can be employed as markers for biochemical and biological systems in immuno-assays, radiographic and electron microscopic investigations of active centers and use as radio pharmaceuticals. Essential is a covalent stable linkage. One simple possibility is the functionaliz ation of peptides and proteins by acylation of, e.g., lysine side chains using succinimyl e sters [70]. Modification of this reactive unit with transition metal complexes such as cyclopentadienyl complexes, sandwich complexes or alkinyl clusters leads to the activated carboxylic acid derivatives which can be isolated and reacted with the free amino group of lysine units in peptides and proteins. Fourier-transform-infrared spectroscopy (FT-IR) at 1900–2100 cm 1 allows the detection of the bonded carbonyl complexes down to a dection limit of the picomol region. The carbonyl-metallo- immunoassay (CMIA) has the advantage that no radioactive compounds are nec essary and by use of different metal organic markers several immuno assays can be carried out simultaneously. Other possibilities are reviewed in [70]. The chemotherapy of cancer with cytotoxic drugs is one of the major approaches. Most cytotoxic anticancer drugs are only antiproliferative which means that the process of cell division is interrupted. cis-Diaminedichloroplatinum(II) (nicknamed cisplatin) is used today routinely against testicular and ovarian cancer. In order to develop new more selective and active anticancer drugs based on platinum, the interaction of the active model compound cisplatin with DNA is important. Structural data have shown that the binding of cisplatin to DNA occurs preferentially at the N7 position of adjacent guanines [72,75,77]. This binding leads to local denaturation of DNA, inhibits the replication process and kills the tumor cells. Because cisplatin possesses two reactive Cl-groups, intrastrand and interstrand crosslinking can occur. Several ruthenium complexes wer e investigated in the interaction with proteins, cytochromes and nucleic acids [78]. The reason is to use these Ru-complexes as luminescence sensors (e.g. optical O 2 sensor), to trigger electron transfer and photo- induced electron transfer in proteins and DNA. For example, elect rogenerated chemoluminescence (ECL) of Ru(phen) 3 2þ (phen: 1 ,10-phenanthroline) can be used to detect the presence of double-stranded DNA (details see [78, p. 642]). Ru(phen) 3 2þ binds strongly to double-stranded DNA, and minimal binding is observed in the presence of single-stranded DNA. If a given single-stranded DNA sequence is immobilized on an electrode, treatment with a suitable target DNA may generate double-stranded DNA which allows the binding of the Ru-complex and by electrode reactions the detection of ECL. Copyright 2005 by Marcel Dekker. All Rights Reserved. III. TYPE I: BINDING OF METALS TO MACROMOLECULAR CARRIERS Several possibilities, as shown in Figure 1, exist for the binding of metal ions/complexes/ chelates to a variety of macromolecules. Methods for the preparation can be subdivi ded into two main routes:  Reaction of a macromolecule bearing suitable ligands or reactive sub stituents for metal ion/complex/chelate binding [equation (10)]  Homo- or copolymerisation of a vinyl monomer (or other polymerizable groups) bearing a metal complex/chelate or a ligand as a metal complex/chelate precursor [equation (11)]. Along both routes linear or crosslinked materials can be used or obtained. Type I compounds with a linear backbone are soluble and can be coated to thin film devices. Crosslinked materials possess in dependence on the amount of crosslinking and procedure of copolymerization pores of different type and size with more or less uniform cross-linked density [79]. One example is amorphous polystyrene crosslinked with divinylbenzene. Non-porous examples are partially crystalline polymers like polyethylene and some inorganic carriers like silica gel. Ligand/metal ion/complex/chelate groups can be distributed on the whole polymer volume or localized only on the carrier surfa ce and connection to the carrier is possible via a direct bond or spacer. All possibilities result in different relativities (properties) of the materials [80,81]. ð10Þ ð11Þ A. Anchoring of Metal Complexes or their Ligands at an Organic Macromolecule 1. General Considerations A macromolecular ligand principally can interact with a metal compound MX n by covalent, coordinative, ionic, charge-transfer or chelate bindings. The interactions with an organic polymer ligand may occur either through monodentate binding (a) (when MX n possesses only one coordination vacancy or group for interaction with the polymer ligand) and polydentate binding either intra-(b) or intermolecular (c) [equation (12)]. In the case of linear or branched organic polymers the macromolecular complexes (a) as a rule, are soluble in organic solvents and their structure is identified rather easy. The solubility of the bridged macrocomplexes (b) decreases; they are more stable and have a less-defined structure. The complexes (c) with the intermolecular bridge bonds are insoluble and difficult to characterize. Exemplarily, it was shown for hydroxyamic acid copolymers that Copyright 2005 by Marcel Dekker. All Rights Reserved. infinite networks are formed when the probability of intermolecular binding of metal ions exceeds 50% [82]. ð12Þ The complex formation on the surface of inorganic carriers preferably occurs by the intramolecular types (a) and (b). The interaction of a polymer ligand with metal ions in aqueous solutions is explained in more detail. Figure 5 shows the dependence of the changes of the hydrogel swelling coefficient of poly(ethylenimine) (PEI) and polyallylamine (PAAHC l) hydrochloride hydrogel and reduced viscosity of its linear polymer on the concentra tion of copper sulfate (C(CuSO 4 )) in aqueous solution (curves a and b) and the ratio of polymer functional groups (C p ) to metal ions concentration (curves c and d) [83]. Characteristic of both investigated systems is the strong compression of hydrogel volume with increasing amount of the metal ion. Attention must be paid to the fact of the influence of the degree of macroligand ionization on the character of the conformational change of the linear segments of the gel. It is seen that under high pH the swelling coefficient of the PEI gel passes through a maximum in the gel-metal ion systems at a concentration of CuSO 4 equal to 8  10 3 mol/L for Cu 2þ (molar ratio of Cu 2þ : PEI ¼ 0.25). The increase of hydrogels swelling degree under complexation with metal ions at high pH can be explained in terms of additional charges in the slightly-charged gel by bivalent metal ions coordinated with the amino groups of PEI. The latter increases the electrostatic energy of the system resulting in an increased swelling coefficient. For the PAA-HCl hydrogel a decrease of the swelling coefficient caused by intramolecular chelation between metal ions and polyligands is observed. This results in additional cross-linking in the network due to the donor– acceptor bonds and compactization of linear parts of polymers between covalently cross- linked points. At low values of pH the complexation proceeds by substitut ion mechanism of protons of the protonized nitrogen atoms of the gel by metal ions avoiding the stage when the polymer chain acquires charge as it was observed at high pH values Copyright 2005 by Marcel Dekker. All Rights Reserved. [...]... By elimination of metal or metal containing groups during the polymerization formation of non-uniform units in the polymer chain Formation of different oxidation states of metals in units in the polymer chain Irregularity in the polymer chain by formation of new chemical bonds between the monomer and the metal containing group Figure 6 Classification of metal containing monomers for polymerization... [195] Polymerizations and copolymerizations of various coordinative-type monomers were intensively investigated in solution or the bulk [4] A great influence on the kind of ligand, metal ion and also solvent on the probability of the polymerization under radicalic initiation was found Due to side reactions often the polymer yield of the coordinativetype monomers are lower compared to the polymer yield of. .. between TiCl4 and the copolymers of styrene and the diallyl esters of dicarboxylic acids [85] For n ¼ 1 or 2, a mixture of complexes with the cis-disposition of 1 and trans-disposition of 2 of the carbonyl groups is formed Increase in the size of the separating bridge (n > 3) precludes the formation of type 1 complexes The complex formation can be influenced also by the nature of the connecting bridge... characterization of the polymers Thermotropic liquid crystalline polymers containing b-diketonato groups (–R–CO– CH2–CO–R) capable of metal ion binding (Cu2þ, Ni2þ) in the main chain of polyesters or in the side chain of polyarylates are described [237] Binding of Pt4þ at poly(ethyleneimine) and other polymers containing 1,2-diimino parts in the polymer chain were prepared for the use in chemotherapy of cancer... growing polymer film surface in order to react with 1,2,4,5-tetracyanobenzene at first to octacyanophthalocyanine and then to oligomeric and polymeric phthalocyanines By ESCA spectra $0.7% of free Cu in the polymeric films were found In dependence of the deposited Cu-film thicknesses of $1.5 till 20 nm adhering films of the polymers 56 with thicknesses of $46 till 230 nm were obtained For the ratio of the... basic polymers such as poly(vinylamine), neutral polymers such as polyalcohols and acidic polymers such as poly(acrylic acid) were investigated using the method of ‘Liquid-Phase Polymer- Based Retention’ for the separation of metal ions from aqueous solution [114 ] Copyright 2005 by Marcel Dekker All Rights Reserved A N-isopropylacrylamide-bound hydroxamic acid copolymer 14 was prepared by the reaction of. .. and spatial mobility of the complexing unit This results in the diffusion of ions in the polymeric medium and allows the ligands bound to the polymer to be more mobile [86] By steric hindrance of the macromolecular chain the formation of a multidentate complex often cannot occur In polystyrene being substituted by bipyridyl groups the formation of a monodentate complex 4 and not of the expected trisbipyridyl... to styrene [174,176] The copolymerization parameters in the copolymerization of styrene (M1) with 33 (M2) are r1 ¼ 0.98, r2 ¼ 1.22 and with 34 (M2, C6H5 instead of C2H5) are r1 ¼ 0.83, r2 ¼ 2.86, respectively [178] The medium values of the molecular weight are in general less then 104 In the case of the copolymerization of trans-Pd[P(C4H9)3]2(C6H4CH ¼ CH2)Cl (M2), the copolymerization parameters r1... show a lower reactivity of the organometallic compound [179] For high molecular weight polymers it is more suitable to prepare the organometallic polymer by polymer analogous reactions at reactive polymers Copyright 2005 by Marcel Dekker All Rights Reserved Only a few papers describe the polymerization of unsaturated monomers with a covalent M–O bond Ziegler–Natta copolymerization of the diisobutylaluminium-alkoxyisopren... during the formation of the complexes of corresponding ions with some copolymers followed by cross-linking of the chains [89–92] The structure of the macrocomplex formed during interaction of the metal ion with the ligand is strictly determined by their nature If then the metal ion is removed and simultaneously the formed stereostructure of the polymer is preserved, the remained polymer ligand has ‘pocket’ . number of macrocycles n (degree of polymerization) with the number of bridged monomers b and the number of end monomers e. n ¼ b=2 þ e=4 ð9Þ Evaluation of some data (determination of number of nitrile. compactization of linear parts of polymers between covalently cross- linked points. At low values of pH the complexation proceeds by substitut ion mechanism of protons of the protonized nitrogen atoms of. with changes in polymer chain conformati on under complex formation must be considered in addition [3]. Bending of a polymer chain by coordination of different ligand groups of one polymer chain