Formation of nonclassical carbonyls of Au3+ in zeolite NaY: characterization by infrared spectroscopy

Adsorption of CO on gold supported in zeolite NaY at 85 K led to the formation of (i) various carbonyls and isocarbonyls typical of the zeolite and (ii) carbonyls formed at cationic gold sites (observed in the 2186-2171 cm(-1) region). Analysis of the behavior of the bands allows their assignment to carbonyls of Au(3+) ions. At temperatures higher than 220 K, CO adsorption led to the formation of a new type of Au(3+)-CO species (2207 cm(-1)). Once formed, these complexes could be transformed into the dicarbonyls Au(3+)(CO)(2) when the sample was cooled to 85 K in the presence of CO. The results are explained by migration of Au(3+) ions to more accessible positions within the zeolite at increasing temperatures. When a CO molecule is already adsorbed, it stabilizes the Au(3+) ion in the new position, and a second CO molecule can be coordinated, thus forming a geminal species. These results are the first evidence of Au(3+)(CO)(2) complexes.     

Time-resolved in situ XAS study of the preparation of supported gold clusters

Incipient-wetness impregnation of gamma-Al(2)O(3) with HAuCl(4) and subsequent removal of chlorine with NaOH, and deposition-precipitation of HAuCl(4) on TiO(2) at pH 7 resulted in supported Au(3+) species. Time-resolved in situ XAS at the Au L(3) edge showed that the Al(2)O(3)-supported oxidic or hydroxidic species were reduced in hydrogen at 440 K to yield small metallic gold clusters. The Au(3+) precursor decomposed to metallic gold in inert atmosphere at 573 K and in oxidizing atmosphere above 623 K. In all atmospheres, initially small clusters were formed that gradually grew with increasing temperature. The TiO(2)-supported species were considerably less stable. In hydrogen and carbon monoxide, Au(0) clusters of 1 to 1.5 nm were formed at room temperature, which was the lowest temperature studied. In inert and oxidizing atmosphere, the Au(3+) precursor decomposed fully to metallic gold at 530 K, as shown by XAS and temperature-programmed experiments. Large clusters were obtained already in the initial stage of reduction. Residual chlorine inhibited the reduction and led to sintering of the gold clusters. Exposure of the TiO(2)-supported catalyst precursor to light or the X-ray beam led to partial reduction, and STEM showed that storage of the reduced gold clusters under ambient conditions led to agglomeration and bimodal cluster-size distributions.     

Tetranuclear Gold(I) Clusters with Nitrogen Donor Ligands: Luminescence and X-Ray Structure of Gold(I) Naphthyl Amidinate Complex

The syntheses and characterization of gold(I) naphthyl, pentafluorophenyl, and trifluoromethylphenyl amidinate complexes are reported. The tetranuclear clusters are obtained from the reaction of Au(tetrahydrothiophene)Cl with the potassium salt of the corresponding amidinate in a THF solvent. The crystal structures of the gold(I) naphthyl, 2, and pentafluorophenyl, 3, amidinates show a short Au···Au distance of ~3. 0 Å typical of compounds having an aurophilic interaction. The gold atoms are arranged in a square (Au···Au···Au = 87°–92°) in the pentafluorophenyl derivative and in a parallelogram (Au···Au···Au = 68°–110°) in the naphthyl amidinate complexes. The naphthyl and trifluoromethylphenyl complexes are visibly luminescent in the solid state at liquid nitrogen temperature displaying asymmetric emission bands at 538 and 473 nm, respectively. The luminescent lifetimes of these species are in the millisecond range indicating phosphorescent processes.     

Synthesis of spherical particles by self-assembly of poly[2-(perfluorooctyl)ethyl acrylate-co-acrylic acid] in supercritical carbon dioxide

Spherical particles were prepared from poly[2-(perfluorooctyl)ethyl acrylateco-acrylic acid] random copolymers (P(POA-co-AA)) by self-assembly in supercritical carbon dioxide (scCO2). The P(POA-co-AA) copolymers with 9:1, 8:2, 7:3, and 6:4 molar ratios of the POA/AA unit completely dissolved in scCO2, however, the solubility was dependent on the POA/AA ratio. The copolymer with the higher AA content had a lower solubility. The scanning electron microscopy (SEM) observations revealed that the spherical particles were obtained in a heterogeneous state at pressures lower than the cloud point pressure. Dynamic light scattering and 1H NMR studies demonstrated that the copolymers formed random copolymer micelles consisting of the shells of the CO2-philic POA units and the cores of the CO2-phobic AA units and main chains. It was found that the formation of spherical particles could be optimized by the manipulation of the CO2 pressure and temperature for the different compositions of the copolymers.     

Novel cathodic electrochemiluminescence of tris(bipyridine) ruthenium(II) on a gold electrode in acidic solution

The novel phenomenon of cathodic electrochemiluminescence on a gold electrode in tris(bipyridine) ruthenium(II) (Ru(bpy)(3)(2+)) solution is described for the first time. A cathodic electrochemiluminescence (ECL) was found to mainly occur at 0.4-0.8 V with continuous potential scanning from 0.2-1.4 V and the ECL peak was observed around 0.68 V, which was quite different from generally reported Ru(bpy)(3)(2+) ECL. Our group speculated that Ru(bpy)(3)(2+) possibly reacts with the gold electrode in the acidic phosphate buffer solution (PBS) to generate luminescence. The possible ECL mechanism was discussed according to the presented results. Moreover, it is revealed that the Au as co-reactant in the Ru-system contributed dominantly to the whole ECL. Therefore, the reaction between Ru(bpy)(3)(2+) and the newly formed Au implied that the inert metal Au could become a promising material for ECL investigations.     

Computer simulations of block copolymer tethered nanoparticle self-assembly

We perform molecular simulations to study the self-assembly of block copolymer tethered cubic nanoparticles. Minimal models of the tethered nanoscale building blocks (NBBs) are utilized to explore the structures arising from self-assembly. We demonstrate that attaching a rigid nanocube to a diblock copolymer affects the typical equilibrium morphologies exhibited by the pure copolymer. Lamellar and cylindrical phases are observed in both systems but not at the corresponding relative copolymer tether block fractions. The effect of nanoparticle geometry on phase behavior is investigated by comparing the self-assembled structures formed by the tethered NBBs with those of their linear ABC triblock copolymer counterparts. The tethered nanocubes exhibit the conventional triblock copolymer lamellar and cylindrical phases when the repulsive interactions between different blocks are symmetric. The rigid and bulky nature of the cube induces interfacial curvature in the tethered NBB phases compared to their linear ABC triblock copolymer counterparts. We compare our results with those structures obtained from ABC diblock copolymer tethered nanospheres to further elucidate the role of cubic nanoparticle geometry on self-assembly.     

Luminescent gold(I) and silver(I) complexes of 2-(diphenylphosphino)-1-methylimidazole (dpim): characterization of a three-coordinate Au(I)-Ag(I) dimer with a short metal-metal separation

The Au(I) and Ag(I) closed-shell metal dimers of 2-(diphenylphosphino)-1-methylimidazole, dpim, were investigated. dpim formed the discreet binuclear species [Ag2(dpim)2(CH3CN)2](2+) (1) when reacted with appropriate Ag(I) salts. Likewise, [Au2(dpim)2](2+) (3) and [AuAg(dpim)3](2+) (4) were produced via reactions with (tht)AuCl, tht is tetrahydrothiophene, and Ag(I). Compound 3 exhibits an intense blue luminescence (lambdamax=483 nm) in the solid state. However, upon initial formation of 3, a small impurity of Cl- was present giving rise to an orange emission (lambdamax=548 nm). Attempts to form [Au2(dpim)2]Cl2 yielded only (dpim)AuCl (2), which is not visibly emissive. The rare three-coordinate heterobimetallic complex [AuAg(dpim)3](2+) (4) exhibits intense luminescence in the solid-state resembling that of 3. The crystal structures of 1-4 were determined, revealing strong intramolecular aurophilic and argentophilic interactions in the dimeric compounds. Compound 1 has an Ag(I)-Ag(I) separation of 2.9932(9) A, while compound 3 has a Au(I)-Au(I) separation of 2.8174(10) A. Compound 4 represents the first example of a three-coordinate Au(I)-Ag(I) dimer and has a metal-metal separation of 2.8635(15) A. The linear Au(I) monomer, 2, has no intermolecular Au(I)-Au(I) interactions, with the closest separation greater than 6.8 A.     

Tuning Thermal Gelling Behavior of N-isopropylacrylamide Based Copolymer through Introducing Cucurbit[8]uril Ternary Complex on Side-chain

Thermo-gelation polymers have attracted increasing attention over decades. However, rare facile tuning method of sol-gel transition temperature restricted the wider application. Preceding study indicated that supramolecular interactions demonstrated a powerful means to control the structure and property of polymeric materials. Here we designed an N-isopropylacrylamide(NIPAM) based thermo-sensitive copolymer with naphthyl(Np) on its side chain. Positive-charged side-chain ternary complex was formed with cucurbit[8]uril(CB[8]) and methylviologen(MV~(2+)) via CB[8]-enhanced intermolecular charge-transfer(CT) interaction. Introducing the ternary complex CB[8]/MV~(2+)/Np on side-chain altered microstructure of macromolecular chains and led to a strong tendency for thermo gelation. Altering content of CB[8] and MV~(2+) changed content of the positive-charged side-chain ternary complex and varied gelation temperature. Therefore,introducing supramolecular interaction endowed the hydrogel with tunable gelation property.     

Size- and support-dependent electronic and catalytic properties of Au0/Au3+ nanoparticles synthesized from block copolymer micelles

Supported Au nanoclusters synthesized from diblock copolymer micelles can be reliably prepared with well-controlled sizes and dispersions. For particles with diameters between approximately 1 and 6 nm, the particle size and the support were found to strongly influence the oxygen reactivity, the formation and stabilization of a metal-oxide, and the catalytic activity for electrooxidation of carbon monoxide. The smallest particles studied (1.5 nm) were the most active for electrooxidation of CO and had the largest fraction of oxygen associated with gold at the surface as measured by the Au(3+)/Au(0) X-ray photoemission intensities. Conducting and semiconducting substrates, ITO-coated glass and TiO(2), respectively, were associated with greater stabilization of Au(3+) oxide as compared to insulating, SiO(2), substrates.     

Water-soluble surface-anchored gold and palladium nanoparticles stabilized by exchange of low molecular weight ligands with biamphiphilic triblock copolymers

A study is presented of the stabilization of gold and palladium nanoparticles (NPs) via a place-exchange reaction. Au and Pd NPs of approximately 3.5 nm were prepared by a conventional method using tetraoctylammonium bromide (TOAB) as the stabilizing agent. The resulting nanoparticles, referred to as Au-TOAB or Pd-TOAB, were later used as templates for the replacement of TOAB ligand with poly(ethylene oxide)- b-polystyrene- b-poly(4-vinylpyridine) (PEO- b-PS- b-P4VP) triblock copolymer. This biamphiphilic triblock copolymer was synthesized by atom transfer radical polymerization (ATRP) with control over the molecular weight and polydispersity. The place-exchange reaction was mediated through strong coordination forces between the 4-vinylpyridine copolymer and the metal species located on the surface of the nanoparticles. In addition, the displacement of the outgoing low molecular weight TOAB ligands by high molecular weight polymers is an entropy-assisted process and is believed to contribute to stabilization. The prepared complex, polymer-NP, exhibits greatly improved stability over the metal-NP complex in common organic solvents for the triblock copolymer. Self-assembly in water after ligand exchange resulted in micellar structures of about approximately 20 nm (electron microscopy) with the metal NP found located on the surface of the micelles. The stability of the nanoparticles in water was shown to depend greatly on the grafting density of the copolymer, with high stability (more than 6 months) at high grafting density and low stability, accompanied with irreversible agglomeration, at relatively low grafting densities. The surprising location of the metal NP (for both Au and Pd) on the surface of the micelles in water is explained by the fact that, upon self-assembly in THF/water system, the most hydrophobic chains (i.e., PS) undergo self-assembly first at low water content forming the core, followed by the P4VP (whether or not associated with the metal) forming a shell, and finally the PEO forming the corona. In lower metal content assemblies, the P4VP chains located in the shell undergo swelling in an acidic medium causing a substantial increase in micellar corona size, as confirmed by dynamic light scattering measurements. The present study offers a simple approach for the stabilization of various metal nanoparticles of catalytic interest, using a unique polymeric support that can be dispersed in organic solvents as well as aqueous solutions.     

Au adatoms in self-assembly of benzenethiol on the Au(111) surface

Self-assembly of benzenethiol at low coverage on Au(111) was studied using low-temperature scanning tunneling microscopy. Phenylthiolate species (PhS), formed by thermal dehydrogenation of the parent PhSH molecule, was found to self-assemble into surface-bonded complexes with gold adatoms. Each complex involves two PhS species and one gold adatom. The PhS species form either cis- or trans-geometry relative to each other. At a higher coverage, the complexes coalesce, most likely due to the formation of weak C-H...S hydrogen bonds facilitated by the spatial arrangement of the PhS groups. Our findings thus establish that the self-assembly of arenethiols on the Au(111) surface is driven by gold adatom chemistry, which has recently been found to be the key ingredient in the self-assembly of alkanethiols on gold.     

pH-Dependent spectroscopic and luminescent properties, and metal-ion recognition studies of Re(I) complexes containing 2-(2'-pyridyl)benzimidazole and 2-(2'-pyridyl)benzimidazolate

A series of Re(I) complexes, [Re(CO)(3)Cl(HPB)] (1), [Re(CO)(3)(PB)H(2)O] (2), [Re(CO)(3)(NO(3))(PB-AuPPh(3))] (3), and [Re(CO)(3)(NO(3))(PB)Au(dppm-H)Au](2) (4) [HPB = 2-(2'-pyridyl)benzimidazole; dppm = 2,2'-bis(diphenylphosphinomethane)], have been synthesized and characterized by X-ray diffraction. Complex 1, which exhibits interesting pH-dependent spectroscopic and luminescent properties, was prepared by reacting Re(CO)(5)Cl with an equimolar amount of 2-(2'-pyridyl)benzimidazole. The imidazole unit in complex 1 can be deprotonated to form the imidazolate unit to give complex 2. Addition of 1 equiv of AuPPh(3)(NO(3)) to complex 2 led to the formation of a heteronuclear complex 3. Addition of a half an equivalent of dppm(Au(NO(3)))(2) to complex 2 yielded 4. In both 3 and 4, the imidazolate unit acts as a multinuclear bridging ligand. Complex 4 is a rare and remarkable example of a Re(2)Au(4) aggregate in combination with μ(3)-bridging 2-(2'-pyridyl)benzimidazolate. Finally, complex 2 has been used to examine the Hg(2+)-recognition event among group 12 metal ions. Its reversibility and selectivity toward Hg(2+) are also examined.     

Au(CN)4]- as both an intramolecular and intermolecular bidentate ligand with [(tmeda)Cu(mu-OH)] dimers: from antiferro- to ferromagnetic coupling in polymorphs

Two polymorphic products, [[Cu(tmeda)(mu-OH)}2Au(CN)4][Au(CN)4] (1) and [Cu(tmeda)(mu-OH)Au(CN)4]2 (2), were synthesized from {Cu(tmeda)(mu-OH)}(2)X(2) (tmeda = N,N,N',N'-tetramethylethylenediamine, X = ClO4-, BF4-) and 2 equiv of K[Au(CN)4], and their X-ray structures were determined. Both compounds have [Cu(tmeda)(mu-OH)}2(2+) dimers with [Au(CN)4]- units bound in the axial positions. However, in 1, two trans N-donor cyanides of each [Au(CN)4]- unit bind to adjacent copper(II) dimers, forming a 1-D chain, whereas complex 2 is molecular, with two mono-coordinated [Au(CN)4]- units. The 1-D polymorph 1 is formed from aqueous solution, while the molecular polymorph 2 is obtained with X = BF4- in methanol. The polymorphs have slightly different Cu-O-Cu angles, a key magnetostructural parameter, such that the 1-D chain 1, with an angle of 96.6(2) degrees, shows ferromagnetic interactions with 2J = +57.5 cm(-1) and g = 2.097, whereas the molecular complex 2, with an angle of 98.92(17) degrees, shows antiferromagnetic interactions with 2J = -143.6 cm(-1) and g = 2.047. A similar Cu(II) complex, [[Cu(tmeda)(mu-OH)]2Au(CN)4][ClO4].MeOH (3), was synthesized in methanol when X = ClO4-, in which the [Au(CN)4]- unit bridges the two Cu(II) centers within the dimer in an intramolecular fashion via cis N-donor cyanides. The average Cu-O-Cu angle of 98.4(2) degrees in 3 generates antiferromagnetic interactions with 2J = -64.8 cm(-1) and g = 2.214. Complexes 1-3 represent the first examples of [Cu(tmeda)(mu-OH)]2(2+) dimers with Cu-O-Cu angles under 100 degrees, thereby extending the range of 2J coupling constants for this moiety from 149 to 566 cm(-1). The switch to ferromagnetic interactions in 1 as a result of the coordinating, bridging [Au(CN)4]- anion suggests that cationic, dinuclear moieties that are typically antiferromagnetically coupled may, with an appropriate coordinating counterion, become ferromagnetic units.     

Formation and catalytic activity of spherical composites with surfaces coated with gold nanoparticles

Micelle-supported gold composites with a polystyrene core and a poly(4-vinyl pyridine)/Au shell are synthesized using NaBH(4) to reduce a mixture of micelle and HAuCl(4) in acidic aqueous solution (pH approximately 2). The template micelle with a polystyrene core and a poly(4-vinyl pyridine) shell is formed by self-assembly of block copolymer polystyrene-block-poly(4-vinyl pyridine). The gold nanoparticles coated onto the surfaces of the composites possess an average diameter of about 15 nm. The composites are applied to catalyze the reduction of p-nitrophenol in the presence of NaBH(4), and the results indicate that the kinetic constant of the reaction increases when the composite concentration and the reaction temperature increase. In addition, research results also indicate that composites with high content of gold show higher catalytic activity and higher catalytic efficiency.     

Monolayer-protected gold nanoparticles by the self-assembly of micellar poly(ethylene oxide)-b-poly(epsilon-caprolactone) block copolymer

A study is presented of the preparation of gold nanoparticles incorporated into biodegradable micelles. Poly(ethylene oxide)-b-poly(epsilon-caprolactone) (PEO-b-PCL) copolymer was synthesized by ring-opening polymerization, and the hydroxyl end group of the PCL block was modified with thioctic acid using dicyclohexyl carbodiimide as the coupling reagent. The PEO-b-PCL-thioctate ester (TE) thus obtained was used in a later step to form monolayer protected gold nanoparticles via the thioctate spacer. Gold nanoparticles stabilized with the PEO-b-PCL block (named Au/Block (x/y), where x/y is the mole feed ratio between HAuCl4 and PEO-b-PCL-TE) were prepared and analyzed. Au/Block (1/1), Au/Block (2/1), and Au/Block (3/1) nanoparticles were found to form stable dispersions in the organic solvents commonly used to dissolve the unlabeled block copolymer. The average diameter of the nanoparticles was determined by transmission electron microscopy (TEM) and found to be 6+/-2 nm. Au/Block (4/1) nanoparticle dispersions in organic solvents, on the other hand, were not stable and produced large gold clusters (50-100 nm). Cluster formation was attributed to the low grafting density of the block copolymer, which facilitates agglomeration. For Au/Block (12/1), along the same trend, only an insoluble product was isolated. Micelles in water were prepared by the slow addition of the dilute Au/Block solution in dimethylformamide into a large excess of water with vigorous stirring. Au/Block (1/1) and Au/Block (2/1) formed nanosized structures of 5-7 nm. TEM images of stained Au/Block (1/1) micelles, made in water, clearly showed the formation of core-shell structures. Au/Block (3/1) micelles, on the other hand, were not stable and large agglomerates a few microns in size were observed. The study focuses on the synthesis, characterization, and aggregation behavior of gold-loaded PEO-b-PCL block copolymer micelles, a potential system for drug delivery in conjunction with tissue and subcellular localization studies.     

On the chemical bonding of gold in auro-boron oxide clusters AunBO- (n = 1-3)

During experiment on Au-B alloy clusters, an auro-boron oxide cluster Au2BO- was observed to be an intense peak dominating the Au-B mass spectra, along with weaker signals for AuBO- and Au3BO-. Well-resolved photoelectron spectra have been obtained for the three new oxide clusters, which exhibit an odd-even effect in electron affinities. Au2BO- is shown to be a closed shell molecule with a very high electron detachment energy, whereas AuBO and Au3BO neutrals are shown to be closed shell species with large HOMO-LUMO gaps, resulting in relatively low electron affinities. Density functional calculations were performed for both AunBO- (n = 1-3) and the corresponding HnBO- species to evaluate the analogy between bonding of gold and hydrogen in these clusters. The combination of experiment and theory allowed us to establish the structures and chemical bonding of these tertiary clusters. We find that the first gold atom does mimic hydrogen and interacts with the BO unit to produce a linear AuBO structure. This unit preserves its identity when interacting with additional gold atoms: a linear Au-[AuBO] complex is formed when adding one extra Au atom and two isomeric Au2-[AuBO] complexes are formed when adding two extra Au atoms. Since BO- is isoelectronic to CO, the AunBO- species can be alternatively viewed as Aun interacting with a BO- unit. The structures and chemical bonding in AunBO- are compared to those in the corresponding AunCO complexes.     

Deposition of gold nanoparticles on silica spheres by electroless metal plating technique

A previously proposed method for metal deposition with silver [Kobayashi et al., Chem. Mater. 13 (2001) 1630] was extended to uniform deposition of gold nanoparticles on submicrometer-sized silica spheres. The present method consisted of three steps: (1) the adsorption of Sn(2+) ions took place on surface of silica particles, (2) Ag(+) ions added were reduced and simultaneously adsorbed to the surface, while Sn(2+) was oxidized to Sn(4+), and (3) Au(+) ions added were reduced and deposited on the Ag surface. TEM observation, X-ray diffractometry, and UV-vis absorption spectroscopy revealed that gold metal nanoparticles with an average particle size of 13 nm and a crystal size of 5.1 nm were formed on the silica spheres with a size of 273 nm at an Au concentration of 0.77 M.     

A key to the storage stability of Au/TiO(2) catalyst

The effect of Au(3+) percentage in Au/TiO(2) on its storage stability at room temperature was studied by varying the drying temperature and storage duration of a deposition-precipitation prepared Au/TiO(2) sample. Carefully-designed room temperature storage in a desiccator, in the dark to exclude any interference of light irradiation, was referenced to the freezing storage (255 K) in a refrigerator. The samples were characterized by well-calibrated H(2)-TPR, TEM and TG measurements. Reduction of Au(3+) ions and agglomeration of metallic Au particles were shown to be the main reasons for the deterioration of Au/TiO(2) during desiccator-storage. Correlating the percentage of Au(3+) ions, determined by H(2)-TPR, with the storage stability of Au/TiO(2) for CO oxidation at 273 K revealed that Au/TiO(2) samples with higher Au(3+) percentages (>90%) were much more stable during the desiccator-storage than those with higher percentages of metallic Au. Residual water in fresh Au/TiO(2) before storage showed a promotional effect on gold reduction and agglomeration during storage. By maximizing the percentage of Au(3+) ions and minimizing the residual water in the fresh sample, the deterioration of the Au/TiO(2) catalyst was successfully avoided during desiccator-storage of up to 150 days in dark. A possible mechanism of Au/TiO(2) deterioration during the desiccator-storage was also discussed.     

One-step multifunctionalization of random copolymers via self-assembly

A novel methodology for random copolymer functionalization based on a noncovalent, one-step, multifunctionalization strategy has been developed. Random copolymers possessing both palladated-pincer complexes and diaminopyridine moieties (hydrogen-bonding entities) have been synthesized using ring-opening metathesis polymerization. Noncovalent functionalization of the resultant copolymers is accomplished via (1) directed self-assembly, (2) multistep self-assembly, and (3) one-step orthogonal self-assembly. This system shows complete specificity of each recognition motif for its complementary unit, with no observable changes in the association constants regardless of the degree of functionalization.     

Self-assembly and molecular recognition of a luminescent gold rectangle

A luminescent molecular rectangle [Au(4)(micro-PAnP)(2)(micro-bipy)(2)](OTf)(4) (1.(OTf)(4)) (PAnP = 9,10-bis(diphenylphosphino)anthracene, bipy = 4,4'-bipyridine, X = NO(3)(-) or OTf(-)), synthesized from the self-assembly of the molecular "clip" Au(2)(micro-PAnP)(OTf)(2) and bipy, shows a large rectangular cavity of 7.921(3) x 16.76(3) A. The electronic absorption and emission spectroscopy, and electrochemistry of the metallacyclophane, have been studied. The 1(4+) ions are self-assembled into 2D mosaic in the solid state via complementary edge-to-face interactions between the Ph groups. (1)H NMR titrations ratify the 1:1 complexation between 1(4+) and various aromatic molecules. Comparing the structures of the inclusion complexes indicates an induced-fit mechanism operating in the binding. The emission of 1(4+) is quenched upon the guest binding. The binding constants are determined by both (1)H NMR and fluorescence titrations. Solvophobic and ion-dipole effects are shown to be important in stabilizing the inclusion complexes.