Characterization of the Complexes

Complex-formation between cations and carbohydrates can be readily detected by paper electrophoresis. In 1959, Frahn and Mills published data on the paper-electrophoretic separation of carbohydrates in which, besides severd complexing anions, they also utilized basic lead acetate as the 

Paper electrophoresis is, even in this age of high-performance liquid chromatography (h.p.l.c.), a useful method of analysis. The equipment required is inexpensive, and the technique is simple. It lends itself well to comparison of the coordinating ability of many carbohydrates with any one cation, or of that of several cations with any one carbohydrate. The behavior of Pb proved to be typical of that of complexing cations this behavior was not fully understood by Frahn and Mills, but they made the observation that the mobility of alditols increases with increasing number of threo hydroxyl groups.  

A few years later, in a short but important note. Mills compared the electrophoretic mobilities of some representative polyols with several cations Ca , Sr, and Ba were found to be the most eflFective. Amongst the polyols, c/r-inositol (1) had the greatest mobility with all cations hence, in subsequent studies, it was adopted as the standard. 

Bourne and coworkers studied the electrophoretic behavior of many polyols in copper acetate and basic copper acetate solutions as electrolytes. Although the sugars were found to be rather unresponsive, all alditols tested showed considerable mobility, which was interpreted as being due to complex-formation with Cu ions. Actually, the preponderant ionic species in those solutions are [Cu2(OH)2] and CuOAc the behavior of copper acetate with carbohydrates will be discussed in Section III,2. 

The electrophoretic mobihties of a large number of carbohydrates have been determined in buffered calcium acetate solution. The method is very sensitive for the detection of complex-formation the smallest detectable mobility Mi 0.01, compared to that of c/r-inositol) represents less than 1 % of complex-formation. All carbohydrates that have two vicinal hydroxyl groups on a six-membered ring or on an acyclic chain, or cis on a five-membered ring, show some mobihty only derivatives lacking vicinal hy- 

---

Evidence for the formation of such a complex was obtained from IR spectroscopy [68] of the solid residue obtained by the treatment of MA with Fe(acac),. Characterization of the complex by the ultraviolet (U V) spectral method also indicated the formation of the complex [68]. Misra et al. have carried out grafting of vinyl mono-... 

Other aspects of these copolymerizations were studied including some kinetic features, molecular weights (which were low), the extent of branching due to side reactions on the furan ring, and the characterization of the complex formed between 2-furaldehyde and BF3 Et20. 

The technique of DDIF provides a quantitative characterization of the complex pore space of the rocks to supplement conventional mineralogy, chemistry and petrology analyses. A combination of DDIF, Hg intrusion, NMR T2 and image analysis has become the new paradigm to characterize porous rocks for petroleum applications [62, 61]. 

Interactions between small molecules and HRP are an important source of information about structure and reactivity at the heme group and its immediate environment. Several reviews are available in which ligand binding, and kinetic and spectroscopic characterization of the complexes are described (predominantly for HRP C rather than for other isoenzymes) (8, 23, 24). HRP ligands can be broadly classified into two groups on the basis of whether they bind to the vacant sixth coordination site of heme iron or not. Certain species such as iodide and... 

Carrano CJ, Raymond KN (1978) Coordination Chemistry of Microbial Iron Transport Compounds. 10. Characterization of the Complexes of Rhodotorulic Acid, a Dihydroxa-mate Siderophore. J Am Chem Soc 100 5371... 

The synthesis and characterization of the complexes [RuL(H20)] and [Ru2L(H20)2] in which H4L is ethane-1,T,2,2 -tetra(thioglycolic acid) have been reported. It is proposed from spectroscopic data that each complex contains five-coordinate Ru and that H2L acts as an S202-donoi, while L utilizes eight donor atoms. [RuL(H20)] and [Ru2L(H20)2] react with CO, PPhs, or NO, and the site of addition is proposed to be trans to the aqua ligand in each case. ... 

Ferro, S., Jori, G., Sortino, S., Stancanelli, R., Nikolov, P., Tongon, G., Ricchelli, F., and Mazzaglia, A. (2009). Inclusion of 5-[4-(l-dodecanoylpyridinium)-10,15,20-triphenylpor-phine in supramolecular aggregates of cationic amphiphilic cyclodextrines Physic-chemical characterization of the complexes and strengthening of the antimicrobial photosensitizing activity. Biomacromolecules 10(9), 2592-2600. 

Characterization of the complexing reaction was then conducted in the presence of 0.83 m sodium chloride in the aqueous phase over a temperature range 15°-60°C. In addition, removal of Hs PbCl as a function of the re-agent-to-organic lead ratio Cr/Cl in the presence of 5 wt % NaCl was examined at 30° C using in turn three other dithiocarbamate reagents besides that of sodium diethyl dithiocarbamate. 

Limited structural information is available for silver(I) carboxylates, despite their extensive use as catalysts in the manufacture of urethane polymers. This is in part due to their frequent insoluble and light-sensitive nature making chemical characterization of the complexes difficult. Dimeric structures have been reported for the perfluorobutyrate249 and trifluoroacetate complexes.250 In each case two-fold symmetry was crystallographically imposed. The Ag—O bond lengths were 223-224 pm, and in the more accurate determination of the trifluoroacetate, the Ag—Ag separation was found to be 297 pm. A dimeric structure was also found for the silver(I) complex of 3-hydroxy-4-phenyl-2,2,3-trimethylhexane carboxylate.251 In the asymmetric crystal unit the Ag---Ag separations were 277.8 and 283.4 pm. 

The preparation and spectroscopic characterization of the complex Zn[(NSiMe3)2]2L (L = pyridine) have been reported.163... 

The identification was based on analytical data and chemical behavior. Only in the 1950s were physical methods like infrared and NMR spectroscopy applied, making further characterizations of the complex possible. Since 1954, a series of other acyl and substituted acyl cations have been isolated and identified.91,643-647... 

Dunayevskiy, Y. Vouros, P. Carell, T. Wintner, E. A. Rebek, J. Jr. 1995. Characterization of the complexity of small-molecule libraries of electrospray ionization mass spectrometry. Anal. Chem., 67,2906-2915. 

In order to characterise ion solvation processes, gas phase studies can be performed providing detailed information about individual interactions. These studies can explore changes in some properties between the complexes in the gas phase and the solvated systems in the liquid phase. Theoretical methods can thus provide valuable complementary information not accessible to experimental approaches, both in the characterization of the complexes and in the specific mechanism of the relevant interactions. 

The first step in the study of metal complexes is the synthesis or preparation of the complex of interest followed by physicochemical characterization of the complex. Lanthanides rarely behave like transition metal cations and hence the need for different precautions in handling them. The fundamental characteristics and behavior of lanthanides in solution is useful for embarking on the synthesis of lanthanide complexes. Some properties of lanthanides, which are useful, and of direct interest for practical purposes will be recalled here. 

The synthesis of the complex is followed by the most important step of characterization of the complex. The composition and the structural features of both the ligand and complex have to be established before embarking on further studies. There exist many methods by which the composition and structural features of the complexes are studied. Some of the methods are (i) elemental analysis, (ii) X-ray crystallography, (iii) UV-Vis absorption spectra, (iv) infrared spectroscopy, (v) Raman spectroscopy, (vi) thermal methods of analysis such as thermogravimetry, differential thermal analysis, (vii) nuclear magnetic resonance spectroscopy (proton, multinuclear), (viii) electrospray mass spectrometry. Depending upon the complexity of the system, some or all the methods are used in the studies of complexes. 

The oxophilic character of lanthanide is evident from the characterization of the complex (MeCp)3Yb4(/i-Cl)(,(/i3-Cl)(/i4-0)(THF)3 by the reaction of YbCb and YbOCl with MeCp in THF. The crystal structure of the complex shows an oxygen-centred tetrahedral arrangement of Yb atoms with p.-C bridging each edge and p -C 1 over the triangular face formed by the (MeCp)Yb units [137]. Yb-0(/x4-oxide) bond distance range is 2.13(1)— 2.29 (1) A. 

In a very interesting report from 2001, Ciminiello and coworkers [73] reported the isolation and structural characterization of the complex bromotyrosine-derived imidazole alkaloid archerine (38) that was isolated from the Caribbean marine... 

A series of low-spin tris chelate complexes containing bidentate 2-(arylazo)pyridine derivatives has been prepared, while X-ray stmctural characterization of the complex [Co(dmvi)2(phen)]-2CHCl3 (14) showed a pronounced elongation of the Co bonds relative to the low-spin Fe(II) complex (2.17 vs 1.98 A, respectively), consistent with an axial Jahn-Teller distortion. ... 

Krypton complexes may be prepared directly by the reaction of Krp2 with the appropriate binary fluoride, neat or in solution. In some cases, binary fluorides have been prepared in situ using Krp2 as the fluorinating agent. So far, no X-ray crystal structure of any Krp2 complex has been determined, and the characterization of the complexes has rested largely on vibrational spectroscopy. Raman spectroscopy has been especially valuable in studies of these compounds, all of which are of low thermal stability. 

The synthesis of the cts-dichlorobis(1,2-ethanediamine)platinum(IV) ion was first claimed by Heneghan and Bailar. Later, Liu and Doyle reported the optical resolution, physical (IR, NMR, and ORD) and chemical characterization of the complex ion, expressing doubt that the Heneghan and Bailar procedure worked. Liu and Ibers confirmed the characterization of the resolved complex with an X-ray diffraction study, and Liu and Yoo reported some of its substitution reactions. The details of the synthesis of this complex ion do not appear in refs. 2 to 4, but only in a more obscure reference. Perhaps because of this, little work with this interesting complex has appeared, and some workers have attempted to use the original Heneghan and Bailar synthesis, which, according to Liu, yields only the trans isomer. 

---