O objetivo deste estudo ex vivo foi avaliar as alterações químicas e morfológicas na dentina radicular tratada com diferentes lasers de alta potência. Foram selecionados cinquenta caninos superioresque tiveram suas coroas seccionadas transversalmente e os canais radiculares preparados com instrumentos rotatórios de NiTi até o instrumento #50.02. Após o preparo biomecânico, os dentes foram distribuídos em cinco grupos (n = 10) de acordo com o tratamento de superfície: GI - água, GII - NaOCl + EDTA, GIII - NaOCl + EDTA + laser Diodo (980nm), GIV - NaOCl + EDTA + laser Nd:YAG (1064nm) e GV - NaOCl + EDTA + laser Er,Cr:YSGG (2780nm). Os grupos submetidos ao tratamento com laser (GIII, GIV e GV) foram irradiados por 20 segundos em movimento helicoidal com velocidade aproximada de 1,5 mm/s. Em seguida, os dentes foram clivados e então submetidos à análise da composição orgânica e inorgânica por espectroscopia Raman (cts), quantificação de elementos químicos por espectroscopia de raios X por dispersão em energia (EDS) (wt%), e avaliação da morfologia por microscopia eletrônica de varredura (MEV). Os dados obtidos foram submetidos à análise estatística (ANOVA, p<0,05), considerando as variáveis tratamento de superfície e terço radicular. Nenhum dos tratamentos de superfície avaliados alterou a intensidade do pico de mineral (cts) (p=0,183). O grupo irradiado com Er,Cr:YSGG diminuiu significativamente a intensidade do pico de colágeno (cts) (290,7 ± 41,7) quando comparado aogrupo tratado com água (328,3 ± 63,5) e ao grupo tratado com NaOCl e EDTA (333,9 ± 55,8) (p<0,05). O grupo irradiado com Er,Cr:YSGG também apresentou maior razão mineral/colágeno (9,5 ± 1,1) quando comparado aos grupos tratados com água (7,7 ± 1,5), NaOCl + EDTA (8,0 ± 1,4) e Diodo (8,2 ± 1,6). Em relação aos terços radiculares, as intensidades do pico mineral e do pico de colágeno apresentaram aumento crescente de cervical para apical (p<0,05) em todos os grupos avaliados, resultando em razão mineral/colágeno menor para o terço cervical, quando comparado aos terços médio e apical. A análise por EDS não apresentou diferença entre os grupos estudados tanto para os elementos químicos avaliados individualmente, assim como para a razão Ca/P (p<0,05). A MEV mostrou que o grupo irradiado com Diodo apresentou superfície de matriz orgânica amorfa, enquanto queo laserEr,Cr:YSGG proporcionou maior remoção de dentina intertubular com formação de crateras, e o grupo irradiado com Nd:YAG promoveu fusão da dentinacom selamentodos túbulos dentinários. Conclui-se que nenhum dos tratamentos de superfície avaliados foi capaz de promover alterações no conteúdo inorgânico da dentina radicular; o tratamento com NaOCl, EDTA, e irradiação Er,Cr:YSGG alterou a estrutura de colágeno. O uso do laser promoveu alterações morfológicas, independentemente do tipo de laser utilizado, quando comparado aos grupos não irradiados / The aim of this ex vivo study was to evaluate the chemical and morphological changes in root dentin treated with different high power lasers. Fifty maxillary canines were selected and had their crowns sectioned transversely and the root canals prepared with NiTi rotary instruments to the instrument # 50.02.After biomechanical preparation, the teeth were distributed into five groups (n=10) according to the surface treatment: GI - water, GII - NaOCl + EDTA, GIII - NaOCl + EDTA + Diode (980nm), GIV - NaOCl + EDTA + Nd:YAG (1064nm) and GV - NaOCl + EDTA + Er,Cr:YSGG (2780nm). The groups subjected to laser treatment were irradiated for 20 seconds by performing helical motion along the rootwith a speed of approximately 1.5 mm/s. Samples were bisected, exposing the treated surface and were subjected to the analysis of organic and inorganic composition by Raman spectroscopy (cts), elements quantification by energy-dispersive x-ray spectroscopy (EDS) (%), and had the morphology evaluated by scanning electron microscope (SEM).Data were submitted to statistical analysis (ANOVA, p <0.05), considering the variables surface treatment and root third. None of the evaluated surface treatments alter the mineral peak intensity (cts) (p = 0.183).The group irradiated with Er,Cr:YSGG significantly reduced the intensity of collagen peak (cts) (290.7 ± 41.7) compared with the watertreated group (328.3 ± 63.5) and the group treated with NaOCl and EDTA (333.9 ± 55.8) (p <0.05). The group irradiated with Er,Cr:YSGG also showed higher mineral/collagen ratio (9.5 ± 1.1)compared to the group treated with water (7.7 ± 1.5), NaOCl and EDTA (8.0 ± 1.4) and diode 980 nm (8.2 ± 1.6). Both collagen and mineral peak intensities increased from cervical to apical root thirds (p<0.05)in all groups evaluated, resulting in lower mineral/collagen ratio to the cervical third when compared to middle and apical thirds. EDS analysis found no difference between the chemical elements as well as the Ca/P ratio between the studied groups (p <0.05). SEM showed that the group irradiated with 980 nm diode had an amorphous organic matrix surface, while the Er,Cr:YSGG provided greater removal ofintertubular dentin forming craters, and the group irradiated with Nd:YAG promoted fusion of dentin, sealing the dentinal tubules. It is concluded that none of the surface treatments evaluated were able to promote changes in the inorganic content of the root dentin; treatment with NaOCl, EDTA, and irradiated withEr,Cr:YSGG alter the collagenstructure. The use of laser promoted morphological changes, regardless the type of laser used, when compared to non-irradiated roots

Radiation polymerization is a rapid, sustainable process, requiring no environmentally damaging solvents and less energy than thermal polymerization methods. This process is used extensively each year to produce millions of tons of films, coatings, inks, and adhesives. In this work, kinetic- and property-control strategies were developed for three underdeveloped areas of radiation polymerization: free-radical electron beam (EB) polymerization, free-radical/cationic hybrid photopolymerization, and cationic shadow cure. Raman spectroscopy, an analytical technique for studying photopolymerization kinetics, was established as a method of determining the conversion of EB-initiated polymer films. This technique, in conjunction with dynamic mechanical analysis (DMA), was used to investigate the impact of chemical structure on the magnitude of EB dose rate effects (DREs). A strong correlation was determined between the DRE magnitude and monomer size, which may be attributed to chain transfer opportunities. A preliminary predictive relationship was developed to estimate the magnitude of the DRE using the property shift caused by changes in dose, enabling scale-up of process variables for polymers prone to dose rate effects. In addition, a protocol was developed to produce films with equivalent energy deposition for both EB and photopolymerizations, allowing the effect of the initiating radiation to be studied. Distinct kinetic and physical property differences were shown in the resulting EB- and photo-initiated films, despite equivalent initiation energies and energy rates. Monomer chemistry was determined to be an important factor in the magnitude of these differences. In order to control the phase separation that can occur in free-radical/cationic hybrid systems, the cationic AM mechanism was promoted through a hydroxyl group located on the (meth)acrylate, covalently bonding the (meth)acrylate and epoxide networks. The impact of the AM mechanism on the reaction kinetics and physical properties was studied using real-time Raman spectroscopy and DMA to compare a hydroxyl-containing acrylate and methacrylate to non-hydroxyl-containing controls. The promotion of the AM mechanism improved epoxide conversion and network homogeneity. The affect on the (meth)acrylate kinetics correlated to the propagation rate of the neat (meth)acrylate. It was also demonstrated that the glass transition temperature of the hybrid system could be controlled by varying the ratio of (meth)acrylate to epoxide. Cationic shadow cure, which offers a means of circumventing the light penetration limitations in photopolymerization, was modeled using a central composite design. This model was shown to be predictive of both shadow cure length and gel fraction while varying effective irradiance, exposure time, exposure area, and sample depth. Moreover, the model helped ascertain the impact of each variable and its interactions: shadow cure length was most influenced by sample depth, but the gel fraction was reliant on the other three variables. Active center mobility was also qualitatively tracked, and it was established that the section of solid polymer formed during illumination was restricting the movement of the active centers, preventing complete cure. Through this discovery, a new method of shadow cure was developed, termed transferable shadow cure (TSC). This new method separates the initiation and propagation mechanisms, and, as the name suggests, allows for the active-center-containing monomer to be transferred to areas unreachable by light before solidifying. Conversion of the TSC, as determined via Raman spectroscopy, was also modeled using a central composite design. The model predicts TSC conversion is equally dependent on effective irradiance, sample depth, and exposure time, but independent of exposure area. Through the development of control strategies in these three areas, this work provides a better fundamental understanding of radiation polymerization, as well as guidelines that aid in product design and technology expansion.

Several different laser remote sensing techniques related to the detection of trace chemical species were studied. In particular, a Differential-Absorption lidar (DIAL), a Laser-Induced-Breakdown Spectroscopy (LIBS) lidar, and a Raman lidar were studied. Several of the laser spectroscopic techniques that were used were common throughout these different studies. More precisely, 10.6 μm CO2 laser related spectroscopy was common for the DIAL and LIBS studies, and 266 nm Nd:YAG laser related spectroscopy was used for the LIBS and Raman studies. In the first system studied a tunable CO2 DIAL system was developed for the first time to our knowledge for the potential detection of the explosive Triacetone Triperoxide (TATP) gas clouds. The system has been used to measure gas samples of SF6, and has shown initial absorption measurements of samples of TATP contained within an enclosed optical absorption cell. DIAL/Lidar returns from a remote retroreflector target array were used for the DIAL measurements after passage through a laboratory cell containing the TATP gas. DIAL measured concentrations agreed well with those obtained using a calibrated Ion Mobility Spectrometer. DIAL detection sensitivity of the TATP gas concentration in the cell was about 0.5 ng/μl for a 0.3 m path-length. However, the concentration of TATP was found to be unstable over long periods of time possibly due to re-absorption and crystallization of the TATP vapors on the absorption cell windows. A heated cell partially mitigated these effects. In the second set of studies, a Deep UV LIBS system was developed and studied for the remote detection of solid targets, and potentially chemical, biological, and explosive substances. A 4th harmonic Q-Switched Nd:YAG laser operating at 266 nm was used for excitation of the LIBS plasma at standoff ranges up to 50 m . The LIBS plasma emission covering the range of 240 – 800 nm was enhanced by use of a nearly simultaneous 10.6 μm CO2 laser that increased the LIBS plasma emission by several orders of magnitude. The emission spectrum was used to detect and identify the species of interest. Plasma temperatures on various solid substrates were measured. An increase in the plasma temperature of about 5000 K was measured and analyzed, for the first to our knowledge, due to the addition of the CO2 laser pulse to the LIBS plasma generated by the Nd:YAG laser. An optimum temporal overlap of the two laser pulses was found to be important for the enhancement. Finally, in a third related lidar system, initial 266 nm Raman lidar studies were conducted at detection ranges of 15 m. However, significant spectroscopic background interferences were observed at these wavelengths and additional optical filtering is required.

This thesis presents results of studies using the technique of surface-enhanced Raman scattering (SERS) spectroscopy to investigate surface processes occurring on gold during electrochemical experiments in thiosulfate solutions and during leaching in ammoniacal copper(II) thiosulfate systems. The gold SERS electrode was characterised using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), linear sweep voltammetry (LSV) and cyclic voltammetry (CV). SEM investigations of the SERS activated gold surface showed the presence of electrodeposited dendrites with nanoscale features. XRD studies of the dendrites showed them to be polycrystalline with a large proportion of Au(111). Rotating disk electrode (RDE) studies of polished and SERS electrodes were undertaken in order to clarify the electrochemistry of various thiosulfate systems. The ex situ techniques of XPS and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy were used to determine the presence of sulfur, copper and nitrogen on leached or electro-oxidised surfaces. Voltammetric methods were used to determine sulfur and copper surface coverages at various potentials in sulfide, thiosulfate and ammoniacal copper(II) thiosulfate media. The electro-oxidation of sulfide was examined as a model system in order to identify spectral features and coverage associated with various potential-dependent sulfur layers. In the hydrogen evolution region, a surface layer formed by underpotential deposition in acid and basic media was characterised by a gold-sulfur stretching band, Au-S, attributed in the literature to a monoatomic stretching mode of sulfur bonded to gold. The surface coverage in this potential region was limited to 0.35 ML, representing adsorption in a (3x3)R30 structure. Bands were found to be absent that would have indicated the adsorption of SH– species as has been reported in the literature. A facile change in the position of the Au-S band with potential, unaccompanied by Faradaic processes, was seen when the adsorbed (3x3)R30 sulfur layer was examined in a sulfide-free solution. This may indicate a change in sulfur adsorption sites with potential in the hydrogen evolution region. At potentials above the S II/S0 reversible value in sulfide solutions, the surface coverage increased and S-S bands were observed, indicating the formation of an adsorbed polysulfide species, Au-Sn. A change in the position of the Au-S band was seen to accompany the formation of the S-S bands. As coverage further increased, bands due to S-S-S bending, S-S-S, developed that were characteristic of cyclo octasulfur, S8. On removal from sulfide solution and rinsing, a characteristic SERS spectrum was observed ex situ. The spectrum showed a characteristic S-S at 460 cm-1 and Au-S at 325 cm-1 and was assigned to an adlayer of S8 adsorbed on gold in a crown configuration, Au S8. Gold was polarised in thiosulfate solutions at a potential at which gold dissolution is known to occur. In situ SERS spectra showed bands characteristic of S-S bonding and Au2S to occur after 1 hr for thiosulfate with sodium and ammonium counter-ions and for both systems in the presence of ammonia. XPS studies of polished gold held in sodium thiosulfate under these conditions showed S 2p binding energies corresponding to metal sulfide and pyritic sulfur, S22-. After 72 hrs at the mixed potential in air saturated sodium thiosulfate, SERS investigations showed a spectrum with Au-S8 characteristics. XPS studies on a polished electrode under these conditions showed a third type of S 2p binding with a binding energy between that of pyritic sulfur and S8. The sodium thiosulfate system showed an adsorbed tetrathionate-like surface species, Au-S4O6, to be present at the mixed potential and to disappear with increased potential prior to the formation of bulk S8 via an Au-S8 intermediate. In the presence of the ammonium cation at high potentials, Au-Sn bands appear in the presence of a more intense and broad Au-S characteristic of gold sulfide, Au2S. This was assigned to a mixed gold sulfide/polysulfide phase, Au2S/Sn. With addition of ammonia, the surface species Au S4O6, Au2S/Sn and, tentatively, adsorbed NH3 were observed above the mixed potential. For gold in air-saturated copper(II) ammoniacal thiosulfate media, bands due S-S at 382 cm-1 and symmetric S-O stretching, symS-O, at 1017 cm-1 developed during leaching at the mixed potential. These modes diminished and, when rinsed and examined in water, were replaced by a single band at 255 cm 1 assigned to a metal sulfide stretch. In typical leach solutions, sulfur and copper coverages showed a 2:1 atomic ratio after leaching for 16 h. Ex situ ATR and XPS studies showed that ammonia was adsorbed to a surface copper sulfide. Kinetic studies using atomic absorption spectroscopy (AAS) to measure gold in solution showed that the ammoniacal copper(II) thiosulfate leaching solution exhibited higher dissolution rates in the presence of the sodium counter ion than the ammonium. Thiourea as an additive to thiosulfate solutions was seen to disrupt S-S bonding in both Au-S8 and Au2S/Sn surface structures.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

<p>Crystallization of C₆₀ and C₇₀ from organic solution often leads to the formation of new solvates and other fullerene compounds. In the present thesis, a number of such solvates were obtained and their phase transitions studied using <i>in situ</i> "in solution" techniques. New fullerene materials can be also obtained using High Pressure High Temperature (HPHT) treatment. The formation of C₆₀ polymers in thin films and bulk samples has been studied in situ over a wide pressure-temperature range.</p><p>New methods for single-crystal growth of fullerenes and their compounds have been developed. It was found by <i>in situ</i> "in solution" XRD and Raman spectroscopy that solvate C₆₀ crystals with benzene, toluene and hexane are stable only in equilibrium with their solution. Their melting points coincide with the maximum in the temperature dependence of solubility. C₇₀ solvates grown from these solutions are stable out of solution, and decompose above the boiling points of the solvents. Vibrational signatures were found for the C₆₀ and C₇₀ solvates which are very similar to these for fullerene-sulfur compounds obtained as thin films and single crystals. A new C₇₀S₈ compound was obtained as relatively large single crystals. </p><p>C₆₀ polymerisation under HPHT conditions was studied on thin films and showed a thickness effect on the phase transition around 20 GPa. Superhard and superelastic films were obtained by treatment at 23 GPa and 570K. In situ Raman and XRD studies were performed on bulk samples at pressures up to 27 GPa and temperatures up to 850K. Below 13 GPa, only one- and two-dimensional polymers were found to form during the heating. The observed polymerisation pathway suggests a gradual increase in polymerisation. Above 18 GPa, the <i>in situ</i> Raman spectra obtained during heating remained almost unchanged. The XRD study showed that heating at 830K and 13 GPa leads to the formation of a rhombohedral phase with a volume per C₆₀ molecule of 560-570 ų/M, which is below the value for two-dimensional polymers. Nevertheless, no superhard, highly dense phases were observed under these conditions, in contrast to previous studies.</p>

<p>Confocal microscopy has been used as a tool for studying adsorption of biomolecules to individual chromatographic adsorbent particles. By coupling a fluorescent dye to protein molecules, their penetration into single adsorbent particles could be observed visually at different times during batch uptake. By relating the relative fluorescence intensity obtained at different times to the value at equilibrium, the degree of saturation versus time could be constructed. The use of two different fluorescent dyes for protein labeling and two independent detectors, allowed direct observation of a two-component adsorption process. The confocal technique was also applied for visualization of nucleic acids. Plasmid DNA and RNA were visualized with fluorescent probes that binds to double stranded DNA and RNA respectively. Confocal measurements following single component adsorption to ion exchange particles, revealed an interesting phenomenon. Under certain experimental conditions, development of "inner radial concentration rings" (i.e. adsorbed phase concentrations that are higher at certain radial positions within the particle) were observed. Some examples are given that show how such concentration rings are formed within a particle.</p><p>Methods were also developed for measurement of the spatial distribution of immobilized functional groups. Confocal microscopy was used to investigate the immobilization of trypsin on porous glycidyl methacrylate beads. Artefacts relating to optical length differences could be reduced by use of "contrast matching". Confocal microscopy and confocal micro-Raman spectroscopy, were used to analyze the spatial distribution of IgG antibodies immobilized on BrCN-activated agarose beads. Both these measurement methods indicate an even ligand distribution. Finally, confocal Raman and fluorescence spectroscopy was applied for measurement of the spatial distribution of iminodiacetic- and sulphopropyl groups, using Nd3+ ions as fluorescent probes. Comparison of different microscope objectives showed that an immersion objective should be used for measurement of wet adsorbent particles.</p><p><i>Direct experimental information from the interior of individual adsorbent particles will increase the scientific understanding of intraparticle mass transport and adsorption mechanisms, and is an essential step towards the ultimate understanding of the behaviour of chromatographic adsorbents.</i></p>

<p>In this thesis, volumetric, optical and vibrational properties of H₂O were studied at high pressures by combining techniques of Raman spectroscopy, interferometry and optical imaging. Pressures up to 7 GPa were generated in the diamond anvil cell (DAC), entering the stability fields of liquid water and ices VI, VII and VIII. </p><p>A new integrated system for Raman, interferometric and optical-imaging studies has been built up. Utilizing the interferometric patterns formed between closely-spaced diamond anvils, the system allowed the complete monitoring and control of <i>pVT</i>-conditions of studied ices, as well as the determination of their dispersive properties in the visible range using the Airy equation and Cauchy formulation. This setup and technique thus represent a novel tool for the precise determination of equations of state (EOSs) of transparent materials, including fluids and low-Z materials. </p><p>Data-sets on thermal pressure were obtained from heating/cooling experiments carried out on the liquid water and used for checking the mutual consistency between published EOSs. A <i>pVT</i>-EOS for ice VIII and room temperature isotherms for ices VI and VII at 300 K were derived by combined methods of interferometry and imaging. While the agreement with the available EOSs of ices VII and VIII is very good, some inconsistent EOSs of ice VI were identified in the present study.</p><p>The technique of micro-Raman spectroscopy was applied for the monitoring of phase transformations, identification of various ice phases and for studying the response of vibrational symmetry modes to varying conditions. Analysis based on the combination of the <i>pT</i>-dependencies of the vibrational frequencies with the <i>pVT</i>-EOSs showed that, in the studied ices, the implicit volume-driven contributions dominate over the explicit phonon effects in the total temperature-induced changes in vibrational frequencies. The results provide valuable insight on the anharmonic effects and interactions in these molecular solids.</p>

Carboxymethyl cellulose (CMC) is produced commercially in a two-stage process consisting of a mercerization stage, where the pulp is treated with alkali in a water alcohol solution, followed by an etherification stage in which monochloroacetic acid is added to the pulp slurry. In this thesis an extended mercerization stage of a spruce ether pulp was investigated where the parameters studied were the ratio of cellulose I and II, concentration of alkali, temperature and retention time. The influence of the mercerization stage conditions on the etherification stage, were evaluated as the degree of substitution (DS) of the resulting CMC and the filterability of CMC dissolved in water at a concentration of 1%. The DS results suggested that the NaOH concentration in the mercerization stage was the most important of the parameters studied. When the NaOH concentration in the mercerization step was low (9%), a high cellulose II content in the pulp used was found to have no negative impact on the DS of the resulting CMC compared with pulps with only cellulose I. However, when the NaOH concentration was high (27.5%), pulps with high content of cellulose II showed a lower reactivity than those with only cellulose I with respect to the DS of the CMC obtained after a given charge of NaMCA. The results obtained from the filtration ability study of CMC water solutions suggested that both the amount of cellulose II in the original pulp and the temperature had a negative influence on the filtration ability whereas the NaOH concentration in the mercerization stage had a positive influence. The filtration ability was assumed to be influenced highly by the presence of poorly reacted cellulose segments. A retention time between 1-48 h in the mercerization stage had no effect on either the DS or the filtration ability of the CMC. Using NIR FT Raman spectroscopy molecular structures of CMC and its gel fraction were analyzed with respect to the conditions used in the extended mercerization stage. Here it was found that the alkaline concentration had a very strong influence on the following etherification reaction. FT Raman spectra of CMC samples and their gel fractions prepared with low NaOH concentrations (9%) in the mercerization stage indicated an incomplete transformation of cellulose to Na-cellulose before carboxymethylation to CMC. Low average DS values of the CMC, i.e. between 0.42 and 0.50, were yielded. Such CMC dissolved in water caused very thick and semi solid gum-like gels, probably due to an uneven distribution of substituting groups along the cellulose backbone. FT Raman spectra of CMC mercerized with alkaline concentrations at 18.25 and 27.5% in the mercerization stage indicated, however, that all of the cellulose molecules were totally transferred to CMC of high DS, i.e. between 0.88 and 1.05. When dissolved in water such CMC caused gels when they were prepared from ether pulp with a high fraction of cellulose II.

This thesis describes the synthesis, structure, equilibriaand other properties of novel thallium(III) monomeric andplatinum-bonded complexes with nitrogen donor ligandsethylenediamine, diethylenetriamine, triethylenetetramine,porphyrin, 2,2'-bipyridine and 1,10-phenanthroline in solutionand in solid. The existence of three complexes withthe general formula[Tl(en)n]3+(n = 1-3) and their overall stability constantshave been established in pyridine. All three complexes wereidentified by their205Tl and1H NMR chemical shifts and205Tl-1H coupling constants. The formation process of thecomplexes was followed by1H NMR spectroscopy. The crystal structure of[Tl(en)3](ClO4)3was determined; the thallium(III) ion isN-coordinated in a distorted octahedral geometry. Two [Tl(dien)n]3+(n = 1-2) complexes were proved to exist insolution and the structure of the bis-complex [Tl(dien)2]2+inu-facialisomers was determined in solid. In addition,crystal structures of [Tl(en)2CN](ClO4)2with cyanide bridging between two Tl(en)2units forming an infinite chain structure and of[Tl(tren)2(CN)2](ClO4) with a distorted pseudo-octahedral coordinationaround thallium were determined. Thallium(III) complexes with2,2'-bipyridine and 1,10-phenanthroline have been studied inDMSO using205Tl,13C and1H NMR spectroscopy. In addition, aseven-coordinated thallium was found in the crystal structureof [Tl(bipy)3(dmso)](ClO4)3, and six-coordinated thallium in pseudo-octahedralgeometry in [Tl(phen)2Cl2](ClO4). The solvated complex [Tl(dmso)6]3+has been prepared using concentrated aqueoussolution of Tl(ClO4)3by a solvent replacement reaction in DMSO, and thewater-free solid compound [Tl(dmso)6](ClO4)3was crystallized from DMSO. The structure of thecomplex [Tl(dmso)6]3+is a regular octahedron with the Tl-O bonddistance 2.224(3) Å. It represents an easy and secure wayto introduce water-free Tl(III) into organic phase withoutreduction. Through several reactions, novel heteronuclear Pt-Tlcomplexes with the composition [(NC)5Pt-Tl(tpp)]2-, [(NC)5Pt-Tl(thpp)]2-, [(NC)5Pt-Tl(bipy)n](n = 1-2), [(NC)5Pt-Tl(en)n-1](n = 1-3) and [(NC)5Pt-Tl(phen)n](n = 1-2), have been synthesized in solution.Multinuclear NMR (195Pt,205Tl,13C and1H), Raman spectroscopy and X-ray diffraction dataare fully compatible with formation of unsupported Pt-Tl bondedcomplexes both in solution and in solid. The huge1J(195Pt-205Tl) spin-spin coupling constants (48-66 kHz) wereobserved by both195Pt and205Tl NMR spectroscopy in solution and they providea strong evidence of formation of the Pt-Tl bond in solution.In all six determined crystal structures of the Pt-Tl compoundsa very short Pt-Tl bond is found with distances2.6117(5)-2.6375(5) Å. The calculated values of Pt-Tlforce constants (1.38-1.91 N/cm) are characteristic for asingle metal-metal bond. In the Pt-Tl compounds, the oxidation state of the metalions is intermediate between the stable states PtII/PtIVand TlIII/TlI, respectively, and this is reflected by their195Pt and205Tl chemical shifts. It turns out that N-donorligands can really stabilize the Pt-Tl bond both in solutionand in solid. The character of the metal-metal bond anditstheoretical basis are discussed. <b>Keywords:</b>Thallium, Platinum, Cyanide, N-donor ligand,Metal-metal bond, Multinuclear NMR, Raman spectroscopy, X-raydiffraction, Equilibrium, Spin-spin coupling.