Intercalation of Re(phen)(CO)3Cl into zirconium phosphate: a water insoluble inorganic complex immobilized in a highly polar rigid matrix

The intercalation of fac-tricarbonylchloro-1,10-phenanthrolinerhenium(i) (Re(phen)(CO)(3)Cl) within zirconium phosphate (ZrP) has been achieved using a hydrated ZrP phase that possesses six water molecules per formula unit. This intercalation occurs only at high solution molar ratios (Re : ZrP, 3 : 1) and is characterized by the emergence of a new phase in the X-ray powder diffraction (XRPD) pattern with an interlayer distance of 15.6 A. The XRPD patterns show a decrease in the crystallinity upon intercalation of the inorganic complex. The MLCT absorption bands of Re(phen)(CO)(3)Cl-containing ZrP materials are red shifted in comparison with the complex in acetonitrile whilst the luminescence spectra at different loading levels are blue shifted up to 30 nm in comparison with the complex in acetonitrile. This blue shift is consistent with the rigidochromic effect. The luminescence lifetime of Re(phen)(CO)(3)Cl within ZrP was increased in comparison with its lifetime in acetonitrile solution but is shorter than that of Re(phen)(CO)(3)Cl in frozen glass and polyesther resins. To our knowledge, this is the first example of a water insoluble metal complex intercalated within the layers of ZrP, which opens up new possibilities in the intercalation chemistry of this lamellar material and in the study of host-guest interactions.     

Room-temperature emission from platinum(II) complexes intercalated into zirconium phosphate-layered materials

The direct ion exchange of chloro(2,6-bis(N-methylbenzimidazol-2-yl)pyridine)platinum(II) ([Pt(Me(2)bzimpy)Cl]+) and chloro(2,2':6',2' '-terpyridine)platinum(II) ([Pt(tpy)Cl]+) complexes within a zirconium phosphate (ZrP) framework has been accomplished. The physical and spectroscopic properties of [Pt(Me(2)bzimpy)Cl]+ and [Pt(tpy)Cl]+ intercalated in ZrP were investigated by X-ray powder diffraction and X-ray photoelectron, infrared, absorption, and luminescence spectroscopies. In contrast to unintercalated complexes in fluid solution, which do not emit at room temperature, both intercalated materials in the solid state and in colloidal suspensions exhibit intense emissions at room temperature. A [Pt(Me(2)bzimpy)Cl]+-exchanged ZrP colloidal methanol suspension gives rise to an emission at 612 nm that originates from a lowest (3)MMLCT[dsigma*(Pt) --> pi*(tpy)] state (MMLCT = metal-metal-to-ligand charge transfer) characteristic of strong Pt...Pt interactions. A [Pt(tpy)Cl]+-exchanged ZrP colloidal aqueous suspension exhibits a strong emission band at 600 nm. The accumulated data demonstrate that at high concentrations, [Pt(Me(2)bzimpy)Cl]+ and [Pt(tpy)Cl]+ ions can serve as luminescent pillars inside the ZrP framework.     

Direct ion exchange of tris(2,2'-bipyridine)ruthenium(II) into an alpha-zirconium phosphate framework

The first direct ion exchange of a luminescent metal complex into an alpha-zirconium phosphate framework has been accomplished. A hydrated form of alpha-ZrP, with an expanded 10.3 A interlayer distance, has been used for the intercalation of Ru(bpy)(3)(2+), resulting in further expansion to 15.2 A. The Ru(bpy)(3)(2+) luminescence band is slightly blue-shifted. High Ru(bpy)(3)(2+) loadings lead to luminescence self-quenching.     

Layered inorganic materials as redox agents: ferrocenium-intercalated zirconium phosphate

The direct intercalation reaction of ferrocene (bis(eta5-cyclopentadienyl)iron(II), Fc) with a highly hydrated layered zirconium phosphate (ZrP) resulted in the formation of the ferrocenium ion (Fc+) within the ZrP material. The Fc+-intercalated ZrP material has an interlayer distance of 10.7 A. The intercalated material was used as an electron acceptor for the oxidation of both ferro-cytochrome c and the excited state of tris(2,2'-bipyridine)ruthenium(II) ([Ru(bpy)3]2+). Upon contact of the material with a 1.5 x 10(-5) M solution of ferro-cytochrome c, the UV-vis absorption spectrum shows the successful formation of ferri-cytochrome c. Luminescence spectroscopy shows that the Fc+-intercalated ZrP material quenches the luminescence of [Ru(bpy)3]2+. The excited-state quenching mechanism of [Ru(bpy)3]2+* by Fc+-intercalated ZrP follows a dynamic plus sphere of action model. The second-order dynamic quenching rate constant kq is 2.2 x 10(8) M(-1) s(-1).     

Excited state properties of 9-amino acridine surface adsorbed onto αZr-phosphate particles

In this report the photo-physical properties of 9-amino acridine (9AA) associated with αZr-phosphate particles (αZrP) is examined. In ethanol solution 9AA exhibits absorption maxima at 425 nm, 402 nm and 383 nm as well as emission bands centered at 455 nm and 483 nm (using 423 nm excitation). The corresponding emission decay is monophasic with a lifetime of 16.5 ns. When αZrP is sonicated in the presence of an ethanol solution of 1 mM 9AA the resulting material exhibits a broad absorption band centered at ～400 nm with shoulders at ～425 nm and ～385 nm and emission bands at 462 nm and 485nm (using 423 nm excitation). Interestingly, the emission decay is biphasic with lifetimes of 1.6 ns and 9.8 ns constituting 57% and 43% of the total emission intensity, respectively. The absence of any shifts in the low angle XRD data suggests that 9AA associates via adsorption onto the exterior surfaces of the αZrP particles. Overall, these results are consistent with different modes of 9AA association to αZrP reflecting different degrees of H-bonding which significantly influences the extent of non-radiative decay from the lowest excited singlet state of 9AA.     

Direct intercalation of bis-2,2',2″,6-terpyridylcobalt(III) into zirconium phosphate layers for biosensing applications

The direct intercalation reaction of [Co(tpy)(2)](2+) with the highly hydrated θ phase of layered zirconium phosphate (θ-ZrP) resulted in the formation of the oxidized [Co(tpy)(2)](3+) ion within the ZrP material. The X-ray powder diffraction patterns showed that the interlayer distance increases from 10.3 ? in θ-ZrP to 14.9 ? in the dry [Co(tpy)(2)](3+)-intercalated ZrP {[Co(tpy)(2)](3+):ZrP} phase. The complex remains electroactive within the layers of ZrP. The formal potential of a carbon paste electrode (CPE) modified with [Co(tpy)(2)](3+):ZrP (E°' = 40.8 mV versus Ag/AgCl, 3.5 M NaCl) is non-pH-dependent. However, the sensitivity of the [Co(tpy)(2)](3+):ZrP-modified CPE for the detection of reduced nicotinamide adenine dinucleotide (NADH) electrooxidation was lower than that of a previously reported CPE modified with [Ru(phend)(2)bpy](2+)-intercalated ZrP. (1) To improve the characteristics of NADH electrooxidation of the [Co(tpy)(2)](3+):ZrP-modified CPE, we included the enzyme diaphorase in solution, which increased the electrocatalytic current for NADH oxidation. A bienzymatic lactate biosensor was constructed and used for lactate sensing.     

NADH Electrooxidation Using Bis(1,10-phenanthroline-5,6-dione) (2,2'-bipyridine)ruthenium(II)-Exchanged Zirconium Phosphate Modified Carbon Paste Electrodes

We present a carbon paste electrode (CPE) modified using the electron mediator bis(1,10‐phenanthroline‐5,6‐dione)(2,2′‐bipyridine)ruthenium(II) ([Ru(phend)₂bpy]²⁺) exchanged into the inorganic layered material zirconium phosphate (ZrP). X‐Ray powder diffraction showed that the interlayer distance of ZrP increases upon [Ru(phend)₂bpy]²⁺ intercalation from 10.3 Å to 14.2 Å. The UV‐vis and IR spectroscopies results showed the characteristic peaks expected for [Ru(phend)₂bpy]²⁺. The UV‐vis spectrophotometric results indicate that the [Ru(phend)₂bpy]²⁺ concentration inside the ZrP layers increased as a function of the loading level. The exchanged [Ru(phend)₂bpy]²⁺ exhibited luminescence even at low concentration. Modified CPEs were constructed and analyzed using cyclic voltammetry. The intercalated mediator remained electroactive within the layers (E°′=–38.5 mV vs. Ag/AgCl, 3.5 M NaCl) and electrocatalysis of NADH oxidation was observed. The kinetics of the modified CPE shows a Michaelis–Menten behavior. This CPE was used for the oxidation of NADH in the presence of Bakers' yeast alcohol dehydrogenase. A calibration plot for ethanol is presented.     

Strong near-infrared luminescence in BaSnO3

Powdered samples of the perovskite BaSnO(3) exhibit strong near-infrared (NIR) luminescence at room temperature, following band-gap excitation at 380 nm (3.26 eV). The emission spectrum is characterized by a broad band centered at 905 nm (1.4 eV), tailing on the high-energy side to approximately 760 nm. The Stokes shift is 1.9 eV, and measured lifetimes in the range 7-18 ms depend on preparative conditions. These extraordinary long values indicate that the luminescence involves a defect state(s). At low temperatures, both a sharp peak and a broad band appear in the visible portion of the luminescence spectrum at approximately 595 nm. Upon cooling, the intensity of the NIR emission decreases, while the integrated intensities of the visible emission features increase to approximately 40% of the NIR intensity at 77 K. Room-temperature photoluminescence (PL) is observed across the Ba(1-x)Sr(x)SnO(3) series. As the strontium content increases, the excitation maximum and band gap shift further into the UV, while the intensity of the NIR emission peak decreases and shifts further into the infrared. This combination leads to an unexpectedly large increase in the Stokes shift. The unusual NIR PL in BaSnO(3) may originate from recombination of a photogenerated valence-band hole and an occupied donor level, probably associated with a Sn(2+) ion situated roughly 1.4 eV above the valence-band edge.     

Spectroscopic studies of the conformational properties of naphthoyl chitosan in dilute solutions

A naphthoyl chitosan derivative was prepared, and its conformations in dilute solutions were characterized with spectroscopic methods, including circular dichroism (CD) spectroscopy and fluorescence emission spectroscopy. The CD spectrum of this polymer showed a negative band at about 295 nm in dimethyl sulfoxide (DMSO), indicating that the polymer adopted a helical secondary structure. A helix reversion occurred at concentrations greater than 1 mg/mL. The intensity of the CD signal decreased with the addition of water to the solution, and this suggested a change from a helical conformation to a looser one as a result of the collapse of intramolecular hydrogen bonds. In the fluorescence emission experiments, two kinds of excimer emission bands were detected at 375 and 425 nm, and they were assigned to a partially overlapped dimer with a twisted geometry and a fully overlapped dimer with a sandwichlike geometry, respectively. Adding water to a solution of naphthoyl chitosan in DMSO resulted in a gradual reduction of the emission intensity at 375 nm, and this implied that the twisted arrangement of the chromophore was destroyed by the presence of water. The relative intensity (i.e., the ratio of the intensity of the excimer emission at 425 nm to that of the excimer emission at 375 nm) depended on the solvent (DMSO, N,N‐dimethylformamide, N,N‐dimethylacetamide, and 1‐methyl‐2‐pyrrolidinone), and this indicated that the conformation of naphthoyl chitosan was solvent‐dependent. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2747–2758, 2004     

Photophysical Properties of Metal Ion Functionalized NaY Zeolite

A series of luminescent ion exchanged zeolite are synthesized by introducing various ions into NaY zeolite. Monometal ion (Eu³⁺, Tb³⁺, Ce³⁺, Y³⁺, Zn²⁺, Cd²⁺, Cu²⁺) exchanged zeolite, rare‐earth ion (Eu³⁺, Tb³⁺, Ce³⁺) exchanged zeolite modified with Y³⁺ and rare‐earth ion (Eu³⁺, Tb³⁺, Ce³⁺) exchanged zeolite modified with Zn²⁺ are discussed here. The resulting materials are characterized by Fourier transform infrared spectrum radiometer (FTIR), XRD, scanning electronic microscope (SEM), PLE, PL and luminescence lifetime measurements. The photoluminescence spectrum of NaY indicates that emission band of host matrix exhibits a blueshift of about 70 nm after monometal ion exchange process. The results show that transition metal ion exchanged zeolites possess a similar emission band due to dominant host luminescence. A variety of luminescence phenomenon of rare‐earth ion broadens the application of zeolite as a luminescent host. The Eu³⁺ ion exchanged zeolite shows white light luminescence with a great application value and Ce³⁺ exchanged zeolite steadily exhibits its characteristic luminescence in ultraviolet region no matter in monometal ion exchanged zeolite or bimetal ions exchanged zeolite.     

Luminescence rigidochromism and redox chemistry of pyrazolate-bridged binuclear platinum(II) diimine complex intercalated into zirconium phosphate layers

The direct intercalation of a pyrazolate-bridged platinum(II) bipyridyl dimer ([{Pt(dmbpy)(μ-pz)}(2)](2+); dmbpy = 4,4'-dimethyl-2,2'-bipyridine, pz(-) = pyrazolate) within a zirconium phosphate (ZrP) framework has been accomplished. The physical and spectroscopic properties of [{Pt(dmbpy)(μ-pz)}(2)](2+) intercalated in ZrP were investigated by X-ray powder diffraction and X-ray photoelectron, infrared, absorption, and luminescence spectroscopies. Zirconium phosphate layers have a special microenvironment that is capable of supporting a variety of platinum oxidation states. Diffuse reflectance spectra from powders of the blue-gray intercalated materials show the formation of a low-energy band at 600 nm that is not present in the platinum dimer salt. The nonintercalated complex is nonemissive in room-temperature fluid solution, but gives rise to intense blue-green emission in a 4:1 ethanol/methanol 77 K frozen glassy solution. Powders and colloidal suspensions of [{Pt(dmbpy)(μ-pz)}(2)](2+)-exchanged ZrP materials exhibit intense emissions at room-temperature.     

A new pyrene-based fluorescent probe for the determination of critical micelle concentrations

A new pyrene-based fluorescent probe for the determination of critical micelle concentrations (CMC) is described. The title compound 1 is obtained in five steps, starting from pyrene. Fluorescence spectroscopic properties of 1 are studied in homogeneous organic solvents and aqueous micellar solutions. In a wide range of organic solvents, probe 1 exhibits a characteristic monomer emission of the pyrene fluorophore, with three distinct peak maxima at 382, 404, and 425 nm. The spectra change dramatically in aqueous solution, where no monomer emission of the pyrene fluorophore is detected. Instead, only strong excimer fluorescence with a broad, red-shifted emission band at lambda(max) = 465 nm is observed. In micellar aqueous solution, a superposition of the monomer and excimer emission is found. The appearance of the monomer emission in micellar solution can be explained on the basis of solubilization of 1 by the surfactant micelles. The ratio of the monomer to excimer fluorescence intensities of 1 is highly sensitive to changes in surfactant concentration. This renders 1 a versatile and sensitive probe molecule for studying the micellization of ionic and nonionic surfactants. For a representative selection of common surfactants, the critical micelle concentrations in aqueous solution are determined, showing excellent agreement with established literature data.     

Absorption and fluorescence of a nonionic detergent in aqueous solution

The absorption and fluorescence spectra of a detergent, polyoxyethylene octylphenyl ether, were measured in water at different concentrations. The absorption spectra had a peak at 275 mμ and a shoulder at 281 mμ. The spectra were independent of concentration below the critical micelle concentration, but the molar extinction coefficients of the peak and the shoulder increased with concentration above the critical micelle concentration. The critical micelle concentration value derived from the absorption data was in good agreement with those obtained by other methods. The fluorescence spectra of the detergent in water were independent of concentration in dilute solutions, if the intensities of the spectra were normalized at the peak at 302 mμ. At higher concentrations, a weak excimer band appeared at 345 mμ, whose intensity increased with concentration. The excimer band manifested itself at a concentration slightly lower than the critical micelle concentration. The main band decreased and the excimer band increased, as the temperature was raised. An excimer band was observed in the same region of the spectra for the pure detergent, either in the solid or liquid state. The equilibrium solid spectra exhibited a very strong excimer emission. It was concluded that the excimers were formed within micelles in the case of aqueous solutions.     

Luminescence of lead chloride and lead bromide single crystals: I. The excitation and emission spectra

The luminescence of very pure PbCl₂ and PbBr₂ single crystals has been studied at liquid nitrogen and liquid helium temperature. At 10 K, PbCl₂, as well as PbBr₂, exhibits three emission bands in the spectral region investigated, viz., one in the ultraviolet part of the spectrum, a second one in the blue and a third one in the red. In addition, PbCl₂ shows a violet emission at 5 K. If, at 80 K, PbCl₂ and PbBr₂ crystals were exposed to ultraviolet radiation for one hour or more, a yellow emission appeared.Thin film absorption spectra of both lead halides are discussed. The band in the low energy region of the absorption spectra is attributed to the creation of a cation exciton.The excitation spectra of the different emissions have been measured. The thin film absorption spectra and the luminescence excitation spectra are strongly correlated. All emissions are preferentially excited in the low energy region of the absorption spectrum, i.e., the region of the cation exciton absorption band. The ultraviolet emission of both lead halides is discussed and attributed to the recombination of cation excitons.     

Chemiluminescence during the oxidation of homogentisic acid

Chemiluminescence (CL) that accompanies the autooxidation of homogentisic acid in the presence of an alkali was studied. Data on the red shift of the CL spectrum at increased medium polarity and the dependence of the luminescence intensity and light efficiency on the reagent concentration were obtained. A CL emitter is supposed to be an excimer formed by two radical dianion molecules of homogentisic acid. Chemiluminescence of an excimer occurs during coproportionation.     

Study of the diffusion of pyrene in silicone polymer coatings by steady state fluorescence technique: effects of pyrene concentration

The concentration dependence of the diffusion coefficient of pyrene in single component and two-component room temperature curing silicone polymer coatings is investigated by the steady state fluorescence technique by measuring the pyrene excimer fluorescence intensity. At pyrene concentrations lower than 10 mM, the intensity of excimer fluorescence is proportional to the concentration and at higher concentrations it deviates from this trend due to concentration quenching. Thermal aging studies show that this concentration quenching can be removed by thermal annealing and the excimer emission intensity approaches the value expected from the trend at lower concentrations. The diffusion coefficient of pyrene at low concentrations in silicone polymer coatings is obtained using the approximate solution of one-dimensional diffusion equation. A modified approach is employed to estimate the diffusion coefficient at higher pyrene concentrations. In this method, the excimer intensity and time scale are shifted, respectively to I_max the maximum value of excimer intensity attained during annealing and t_max, the time taken to reach this. The estimated diffusion coefficients at different pyrene concentrations show a negligible dependence on pyrene concentration in both types of polymers. These results are attributed to the high structural mobility of silicone polymer chains due to their molecular structure.     

Luminescence of ruthenium halide complexes containing a hemilabile phosphine pyrenyl ether ligand

A series of Ru(II) complexes, tcc-RuX2(POC4Pyr-P,O)2 (X = Cl (3), Br (4), I (5)), containing the hemilabile phosphine pyrenyl ether ligand 4-{2-(diphenylphosphino)phenoxy}butylpyrene (POC4Pyr (1)) are reported. The synthesis and spectroscopic properties of both the ligand, POC4pyr (1), and ligand oxide, P(=O)OC4pyr 2, and the solid-state structure of 1 are reported. Complexes 3-5 react rapidly with CO to give complexes ttt-RuX2(CO)2(POC4pyr-P)2 (X = Cl (6), Br (7), I (8)). No pyrene excimer emission is detected from 3-5; however, different intensities of excimer emission are observed for 6-8. The intensity of excimer emission decreases through the series, with 6 showing the most intense response. The emission is solely due to intramolecular pyrene excimers at low concentrations (< or =10(-4) M). Comparison of the UV-vis and steady-state fluorescence spectra shows overlap between the low energy d-d absorption of 7 and 8 with excimer emission (480 nm), suggesting nonradiative energy transfer may be occurring. Once excess CO is removed, complexes 6-8 isomerize to cis-dicarbonyl complexes cct-RuX2(CO)2(POC4Pyr-P)2 (X = Cl (9), Br (10), I (11)). The intensity of excimer emission from 9-11 increases with respect to the excimer emission observed for 6-8, with 9 showing a significant increase in excimer intensity.     

FORMATION OF INTRAMOLECULAR EXCIMER IN ARYL PHOSPHATES AND THEIR REACTIVITIES

The fluorescence spectra of bis(4-methoxyphenyl) hydrogen phosphate and tris(4-meth-oxyphenyl) phosphate showed two emission bands. A longwavelength emission band arose from the intramolecular excimer of two 4-methoxyphenyl groups and a short band arose from a 4-methoxyphenyl group itself. There was a good correlation between the relative intensity of the monomer/excimer emissions and the quantum yield of 4,4′-dimethoxybiphenyl, which was an intramolecular coupling product.     

四(4,4',4'',4'''-N,N-二氨基)四苯乙烯光致发光与分子的构象效应

利用还原偶联方法合成出新化合物四(4,4',4',4''-N,N-二氨基)四苯乙烯（ TDETE）。通过测定该化合物在溶液、掺杂聚合物中及晶体粉末的稳态-瞬态荧光光 谱、荧光量子产率和辐射衰变速率常数等。讨论了分子的构象效应等因素对TDETE 光致发光行为的影响。在一定浓度下TDETE溶液存在着三个发光带,分别为全扭曲 构象分子（位于345nm附近的发光I带）、半扭曲构象分子（位于430nm附近的发光 II带）和激基缔合物（530发光III带）的辐射衰变所致。在聚合物（PMMA）中,一 方面由于分子单键的自由旋转扭曲受到遏制,表现为II带的辐射衰变速率常数(kf 值)增大、同时非辐射衰变速率常数knf值减小;另一方面,TDETE分子之间相互作 用得到加强而有利一缔合物形成,结果,使发光II带和III带合二为一出现强而宽 的发射峰,荧光量子产率从溶液中的0.055提高到0.855。此外,在PMM介制裁中观 测到TDETE分子聚集体在626nm处的发光带（IV）,数粉末态中聚集体IV带的强度骤 增,峰值波长红移至650nm。     

CaS：Ce，Sm的制备及性能表征

采用碳还原法制备了CaS：Ce，Sm样品，并研究了反应机理、还原原理以及灼烧温度对CaS晶格形成和光激励发光的影响。样品的XRD测试表明，采用碳还原法制备的CaS：Ce，Sm样品，具有纯CaS的面心立方结构，晶格常数a=0.569 4 nm，样品的激发光谱是峰值分别位于295 nm和461 nm的宽带谱，样品的荧光光谱是峰值位于503 nm、560 nm、600 nm和655 nm带谱，光激励发光光谱是峰值分别位于500 nm，565 nm和605 nm的宽带谱，光激励激发光谱是峰值位于1 150 nm的宽带谱。