Versatile Phosphite Ligands Based on Silsesquioxane Backbones

Silsesquioxanes are employed as ligand backbones for the synthesis of novel phosphite compounds with 3,3′‐5,5′‐tetrakis(tert‐butyl)‐2,2′‐dioxa‐1,1′‐biphenyl substituents. Both mono‐ and bidentate phosphites are prepared in good yields. Two types of silsesquioxanes are employed as starting materials. The monophosphinite 1 and the monophosphite 2 are prepared from the thallium silsesquioxide derived from a completely condensed silsesquioxane framework (c‐C₅H₉)₇Si₇O₁₂SiOTl. The diphosphite 3 is synthesized starting with the incompletely condensed monosilylated disilanol (c‐C₅H₉)₇Si₇O₉(OSiMePh₂)(OH)₂. For monophosphite 2 , the corresponding trans‐[PtCl₂( 2 )] complex 4 is characterized by NMR spectroscopy as well as by X‐ray crystallography, as the first example of a completely condensed oxo‐functionalized silsesquioxane framework. The coordination of the bidentate ligand 3 towards Pd, Mo and Rh is studied, both by NMR spectroscopy as well as by X‐ray crystallography. Various modes of coordination are shown to be possible. The molecular structures for the complexes trans‐[PdCl₂( 3 )] ( 5 ), cis‐[Mo(CO)₄( 3 )] ( 6 ) and the dinuclear complex [{Rh(μ‐Cl)(CO)}₂(κ²‐ 3 )] ( 7 ) have been determined. In the rhodium‐catalyzed hydroformylation of 1‐octene high activities, with turnover frequencies of up to 6800 h⁻¹, are obtained with these new nanosized phosphorus ligands.     

The Role of pH in the Mechanism of .OH Radical Induced Oxidation of Nicotine

The ^.OH radical induced oxidation of nicotine was studied using pulse radiolysis techniques from pH 1 to 13.6. Theoretical calculations were used to help interpret the experimental results. The bond dissociation enthalpies of all of the C H bonds of nicotine were determined using DFT calculations, coupled with the isodesmic reaction. From time-dependent density functional response theory, estimates were obtained of the location of the dominant transient absorption bands (λ_max), their intensities (electronic oscillator strength, f), and the electronic composition of these transitions. OH radicals as well as other potent oxidants reacted with free nicotine through separated, concerted electron proton transfer, leading mostly to the formation of an alpha-aminoalkyl radical located on the C_2′ carbon of the aliphatic ring ( A_2′ ). Protonated nicotine underwent hydrogen atom abstraction at the C_2′ and N_1′ positions, resulting in the formation of the conjugate acid of A_2′ ( A_2′H⁺ ) and the alkylamine radical cation ( N⁺ ), respectively. Doubly protonated nicotine underwent the same reaction pathways, leading to two corresponding conjugate acid species, protonated at the aromatic nitrogen position: PyrH⁺A_2′H⁺ and PyrH⁺N⁺ _. All these radicals interconverted between each other through hydrolytic reactions. The radical A_2′ and its conjugate acid PyrH⁺A_2′ absorbed 10 times stronger than the N⁺ species, based on calculations of f. From the growth of the transient absorption of A_2′ (λ_max=330 nm, ε=8080 M ⁻¹ cm⁻¹), second-order rate constants were determined: k_(OH+Nic)=6.7×10⁹ M ⁻¹ s ⁻¹, k_(OH+NicH)=1.0×10⁹ M ⁻¹ s⁻¹. The alpha-aminoalkyl radicals decayed by disproportionation to form iminium cations 1 – 5 , which contributed to an increase in the specific conductivity of the basic solutions of nicotine following electron pulse irradiation.     

Thermal Behavior of M +B5O6(OH)4 · 2H2O (M + = K, Rb, Cs) and Polymorphic Transformations of CsB5O8

Phase transformations (dehydration, amorphization, crystallization, polymorphic transitions) and thermal expansion of M ⁺B₅O₆(OH)₄ · 2H₂O (M ⁺ = K, Rb, Cs) compounds and the polymorphic transformations of the CsB₅O₈ compound are investigated using the methods of glass crystallization, thermal X-ray diffraction, and differential thermal analysis (DTA). It is shown that the dehydration of RbB₅O₆(OH)₄ · 2H₂O and CsB₅O₆(OH)₄ · 2H₂O, like KB₅O₆(OH)₄ · 2H₂O, proceeds in two stages. After the first stage of the dehydration (with a loss of three water molecules), all three compounds transform into the amorphous state. At the second stage, the fourth water molecule leaves the amorphous phase. At temperatures above the glass transition point, anhydrous pentaborates MB₅O₈ (M = K, Rb, Cs) crystallize and subsequently undergo polymorphic transformations.     

Structure–Affinity Relationships of Fluorinated Spirocyclic σ2 Receptor Ligands with an Exocyclic Benzylamino Moiety

To identify a potent and selective σ₂ receptor ligand appropriate for development as a positron emission tomography (PET) tracer, several fluorinated analogues of the spirocyclic lead compounds trans- and cis- 6 (N-(2,4-dimethylbenzyl)-3-methoxy-3,4-dihydrospiro[[2]benzopyran-1,1′-cyclohexan]-4′-amine) were designed. In multistep syntheses, a fluorine atom was introduced directly or as a 2-fluoroethoxy moiety on the 2-benzopyran scaffold, on the dimethylbenzylamino moiety, or on the central amino moiety. The σ₁ and σ₂ receptor affinity was determined in receptor binding studies with radioligands. With respect to σ₂ affinity and σ₂/σ₁ selectivity, cis-N-(2,4-dimethylbenzyl)-5-fluoro-3-methoxy-3,4-dihydrospiro[[2]benzopyran-1,1′-cyclohexan]-4′-amine (cis- 15 c , K_i(σ₂)=51 nm ) and cis-N-[4-(fluoromethyl)-2-methylbenzyl]-3-methoxy-3,4-dihydrospiro[[2]benzopyran-1,1′-cyclohexan]-4′-amine (cis- 28 e , K_i(σ₂)=57 nm ) are the most promising ligands. The combination of both structural elements in one molecule, cis-N-[4-(fluoromethyl)-2-methylbenzyl]-5-fluoro-3-methoxy-3,4-dihydrospiro[[2]benzopyran-1,1′-cyclohexan]-4′-amine (cis- 28 c : K_i(σ₂)=874 nm ), resulted in decreased σ₂ and σ₁ affinity. Methylation of secondary amines led to three tertiary methylamines with moderate affinity for both σ receptor subtypes.     

Synthesis of and photodegradation in a series of poly(ethylene terephthalate)–co–4,4′-sulfonyldibenzoate yarns

Phototendering studies of poly(ethylene terephthalate) homopolymer yarn and a series of poly(ethylene terephthalate–co–4, 4′-sulfonyldibenzoate) copolymer yarns have shown that photosensitized degradation occurs more readily in the copolymers than in the homopolymer. A photo-oxidative mechanism involving the second monomer, dibutyl 4, 4′-sulfonyldibenzoate, has been proposed to account for the photosensitization. The photophysical processes in the second monomer, dibutyl 4, 4′-sulfonyldibenzoate, were studied by absorption and luminescence techniques. The lowest excited singlet and triplet in this compound were identified as the ¹(π, π^*) and ₃(π, π^*) states, respectively. The energy levels in the second monomer have been assigned as follows: ¹S₁ ～ 33,000 cm^?1, ¹S₂ ～ 42,000 cm^?1, and ³T₁ ～ 26,000 cm^?1.     

Novel syntheses of an aliphatic series of new dithiocarboxylates and perthiocarboxylates of copper (I) and some of their complexes with triphenylphosphine

ABSTRACT

Copper(I) alkyldithiocarboxylates (1a), (1b) and (1c) of formula [RCS₂Cu]₄ [(1a) R?=?t-Bu, (1b) R?=?n-Bu, (1c) R?=?sec-Bu] and copper(I) alkylperthiocarboxylates (2a), (2b) and (2c) of formula [RCS₃Cu]₄ [(2a) R?=?t-Bu, (2b) R?=?n-Pr, (2c) R?=?cyclohexyl] were prepared from the reaction of Grignard reagents with carbon disulfide, in the presence of CuBr. Cu(I) Dithiocarboxylates (1a) and (1b) were treated with triphenylphosphine to give, respectively, complexes (3a) and (3b) of formula RCS₂Cu(PPh₃)₂ [(3a) R?=?t-Bu, (3b) R?=?n-Bu]. The compounds obtained were characterized by various spectroscopic tools including NMR (¹H, ¹³C, ³¹P) spectroscopy, and single crystal X-ray diffraction.     

Phosphonitrilic chloride. XXVI. Synthesis of cyclophosphazene polymer by polycondensation reaction of tetrachlorodiphenyl triphosphazene and aromatic diamine compounds

Tetrachlorodiphenyl cyclotriphosphazene N₃P₃Cl₄(C₆H₅)₂ (TPC) has been synthesized by Friedel-Crafts reaction. The polycondensation of TPC with aromatic diamine compounds has been carried out in pyridine. The products obtained from the reaction of TPC with aromatic diamine compounds were slightly soluble in polar organic solvents. The molecular weights measured by the method of end group analysis were about 2800 to 10800. The products were amorphous, brown, yellow or white coloured solids. The softening points of all polycondensation products were found to be in the region of 100°C to 120°C. The electrical conductivity of the products obtained from TPC with p-phenylenediamine and p,p′-diaminodiphenyl sulfone was determined to 5 × 10¹² (Ωcm)^?1 and 1 × 10¹⁵ (Ωcm)^?1, respectively.     

Silica‐Supported Zirconium Complexes and their Polyoligosilsesquioxane Analogues in the Transesterification of Acrylates: Part 1. Synthesis and Characterization

Various silica‐supported acetylacetonate and alkoxy zirconium(IV) complexes have been prepared and characterized by quantitative chemical measurements of the surface reaction products, quantitative surface microanalysis of the surface complexes, in situ infrared spectroscopy, CP‐MAS ¹³C NMR spectroscopy and EXAFS. The complex (SiO)Zr(acac)₃ (acac=acetylacetonate ligand) ( 1 ) can be obtained by reaction of zirconium tetraacetylacetonate [Zr(acac)₄] with a silica surface previously dehydroxylated at 500 °C. The complexes (SiO)₃Zr(acac) ( 2 ) and (SiO)₃Zr(O‐n‐Bu) (n‐Bu=butyl ligand) ( 3 ) can be synthesized by reaction of (SiO)₃Zr H with, respectively, acetylacetone and n‐butanol at room temperature. The spectroscopic data, including EXAFS spectroscopy, confirm that in compound 1 the zirconium is linked to the surface by only one Si O Zr bond whereas in the case of compounds 2 and 3 the zirconium is linked to 3 surface oxygen atoms which are sigma bonded. EXAFS data indicate also that the acetylacetonate ligands behave as chelating ligands leading to a hepta‐coordination around the zirconium atom in 1 and a penta‐coordination in 2 . In order to provide a molecular analogue of 1 , the synthesis of the following polyoligosilsesquioxane derivative (c‐C₅H₉)₇Si₈O₁₂(CH₃)₂Zr(acac)₃ ( 1′ ) was achieved. The compound 1′ is obtained by reacting (c‐C₅H₉)₇Si₈O₁₁(CH₃)₂(OH), 4 , with an equimolecular amount of Zr(acac)₄. In the same manner, syntheses of complexes (c‐C₅H₉)₇Si₇O₁₂Zr(acac) ( 2′ ) and of (c‐C₅H₉)₇Si₇O₁₂Zr(O‐n‐Bu) ( 3′ ) were achieved by reaction of the unmodified trisilanol, (c‐C₅H₉)₇Si₇O₉(OH)₃, with respectively Zr(acac)₄ and Zr(O‐n‐Bu)₄ at 60 °C in tetrahydrofuran. Compounds 1′ , 2′ and 3′ can be considered as good models of 1 , 2 and 3 since their spectroscopic properties are comparable with those of the surface complexes. The synthetic results obtained will permit us to study the catalytic properties of these surface complexes and of their molecular analogues with the ultimate goal of delineating clear structure‐activity relationships.     

Spektrometrische Untersuchungen an N,N′-disubstituierten Dithiomalonsäurediamiden und ihren Kobalt(II)-Komplexen

Spectroscopical Investigations on N,N′-Disubstituted Dithiomalonamides and their Co(II)-Complexes The Co(II)-complexes of N,N′-disubstituted dithiomalonamides have been synthesized and characterized. Comparative uv/vis-, ir-, epr-, x-ray-, and n.m.r.-spectral studies of this complexes and of the dithiomalonamides suggest that their Co(II)-compounds are S₄-coordinated square planar inner complexes (CoL₂). The orbital splitting parameters Δ of these complexes have been calculated in the order of less than 20000 cm⁻¹. For compounds CoL₂ by this way the following spectrochemical series of the ligands results: dmma < d cl_mma < dnma < d cl_pma < dpma. All dithiomalonamides investigated in this work exist nearly complete in the dithion-form.     

The association constant of macrocyclic ether–cation interactions in 1,4-dioxane/water mixtures. III. Effect of temperature on the binding

The association constant, K_a of Na⁺ with [12]crown-4, [15]crown-5 and [18]crown-6 crown ethers were determined in a binary mixture, 1,4-dioxane/water (50/50) using a Na⁺ ion selective electrode at different temperatures. K_a values were determined with the relationship, 1/K_a [L_o]^n+m–1 = (1–nP′)ⁿ(1–mP′)^m/P′, for various stoichiometries, (n:m), where P′ is the mole fraction of the complexed cation. The exothermic association constants and the thermodynamic data for cation–macrocycle complexes explained in terms of Eigen–Winkler binding mechanism are given. The binding power found for Na⁺, however, was the highest with [18] crown-6.     

Desulfurization and Denitrogenation Processes to Treat Diesel Using Mo(VI)-Bipyridine Catalysts

High efficiency was found for desulfurization and denitrogenation processes to treat diesel using either the hybrid material {[MoO₃(2,2′-bipy)][MoO₃(H₂O)]}_n or the octanuclear complex [Mo₈O₂₂(OH)₄(di-tBu-bipy)₄] (2,2′-bipy = 2,2′-bipyridine, di-tBu-bipy = 4,4′-di-tert-butyl-2,2′-bipyridine) as catalysts. These processes were employed in a single procedure to simultaneously remove sulfur (dibenzothiophene, 4-methyldibenzothiophene, and 4,6-dimethyldibenzothiophene) and nitrogen (indole and quinoline) compounds from diesel. A reaction time of two hours was sufficient to achieve at least 99.9 % S removal and 97 % N removal. Furthermore, the catalytic systems presented a high capacity to be reused/recycled for consecutive desulfurization/denitrogenation cycles.     

Preparation of cellulose derivatives containing carbazole chromophore

Cellulose derivatives containing long hydrocarbon side chains and the carbazole chromophore are prepared. N‐4′‐Bromobutylcarbazole is first synthesized from carbazole and 1,4‐dibromobutane. Alkylated carbazole is then reacted with cellulose acetate in dimethyl sulfoxide solution to produce cellulose ethers containing the desired chromophore. Polymers containing a mixture of alkyl side chains are also prepared by the subsequent addition of 1‐bromododecane to the reaction mixture. Characterization of the resulting cellulose derivatives by FTIR spectroscopy indicates that the deacetylation of cellulose acetate and the subsequent etherification are both complete. In addition, the incorporation of the carbazole chromophore is clearly shown by ¹H‐ and ¹³C‐NMR spectroscopy. Polymers of different carbazole content, ranging from 2.9 to 1.1 chromophores per anhydroglucose repeat unit, are obtained by varying the reaction conditions. Substitution is found to be controlled primarily by the quantity of alkylating agent introduced while variation of the reaction time has little effect. This method is used to prepare (dodecyl)_y(N‐4′‐carbazolylbutyl)_xcellulose, (decyl)_y(N‐4′‐carbazolylbutyl)_xcellulose, and (butyl)_y(N‐4′‐carbazolylbutyl)_xcellulose. Cellulose acetate can be replaced by (methyl)cellulose as the starting material to obtain analogous products. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2764–2772, 1999     

Synthesis and Characterization of an Epidermal Growth Factor Receptor-Selective RuII Polypyridyl–Nanobody Conjugate as a Photosensitizer for Photodynamic Therapy

There is a current surge of interest in the development of novel photosensitizers (PSs) for photodynamic therapy (PDT), as those currently approved are not completely ideal. Among the tested compounds, we have previously investigated the use of Ru^II polypyridyl complexes with a [Ru(bipy)₂(dppz)]²⁺ and [Ru(phen)₂(dppz)]²⁺ scaffold (bipy=2,2′-bipyridine; dppz=dipyrido[3,2-a:2′,3′-c]phenazine; phen=1,10-phenanthroline). These complexes selectively target DNA. However, because DNA is ubiquitous, it would be of great interest to increase the selectivity of our PDT PSs by linking them to a targeting vector in view of targeted PDT. Herein, we present the synthesis, characterization, and in-depth photophysical evaluation of a nanobody-containing Ru^II polypyridyl conjugate selective for the epidermal growth factor receptor (EGFR) in view of targeted PDT. Using ICP-MS and confocal microscopy, we could demonstrate that our conjugate has high selectivity for the EGFR receptor, which is a crucial oncological target because it is overexpressed and/or deregulated in a variety of solid tumors. However, in contrast to expectations, this conjugate was found to not produce reactive oxygen species (ROS) in cancer cells and is therefore not phototoxic.     

Spiroheterocyclic system. Part IV: Novel azo dye sulpha drugs of spiroheterocyclic naphthenes

Novel azo-dyes have been synthesized by diazotization of 4-amino benzene-4′-(substituted heterocyclo) sulphonamide derivatives and coupling with 1-oxa-4-thia-spiro[4,4]nonan-2-one (I) and/or with l-oxa-4-thia-spiro[4,5]decan-2-one (I′) in acid medium to give the corresponding 3-azo-(4′-substituted benzenesulphonamido)-l-oxa-4-thia-spiro[4,4]nonan-2-one (II-IX) and/or l-oxa-4-thia-spiro[4,5]decan-2-one (II′-IX′] as spiro-ligands. Treatment of these ligands with metal salts of iron (Fe³⁺), copper (Cu²⁺) and mercury (Hg²⁺) as chlorides in ethanolic solution furnished the corresponding metal chelates (II_a-c-IX_a-c) and/or (II′_a-c-IX′_a-c). The compounds were tested in vitro for antimicrobial activity to study the structure-activity relationship.     

The Influence of Extractant Structure on the Solvent Extraction of Uranium(VI) and Thorium(IV) from Nitrate Media by Dialkyl Sulphoxides

The solvent extraction of uranium(VI) and thorium(IV) from sodium nitrate solutions (0·20–6·00 M ) by a series of dialkyl sulphoxides with different structures was studied. For sulphoxides with n-alkyl groups (R₂SO, where R = n-hexyl, n-octyl and n-decyl) using 0·20 M solutions in xylene, the extractions of both uranium and thorium are relatively high, and the values of the separation factor β_Th^U are correspondingly low (≈20). Replacement of an n-hexyl group by a cyclohexyl group has little effect on metal extraction, whilst the introduction of a second cyclohexyl group causes a slight decrease in extraction. Similarly, there is little variation in the extraction of uranium and thorium through the series of asymmetrical compounds RR′SO, where R = n-octyl and R′ = cyclopentyl, cyclohexyl or cyclooctyl. When two aromatic (phenyl) rings are introduced into the sulphoxide, however, the extraction of both metals falls to zero. For the series of isomeric compounds R₂SO with C₈ alkyl groups, the separation factors increase in the order: R = n-octyl, 2-ethylhexyl, 2-octyl, 3-octyl, which is also the order of increasing steric bulk of the alkyl group. For these compounds, slope analysis studies are consistent with the formulation of the extracted metal complexes as UO₂(NO₃)₂(R₂SO)₂ and Th(NO₃)₄(R₂SO)₃. © 1997 SCI.     

Molecular structures and vibrational frequencies for cis-[PdCl2(tmen)] and cis-[Pd(N3)2(tmen)]: A DFT study

Theoretical molecular structures of the complexes cis-[PdCl₂(tmen)] and cis-[Pd(N₃)₂(tmen)] (tmen = N,N,N′,N′-tetramethylethylenediamine) were investigated using B3LYP/DFT method. The calculated molecular parameters, bond distances and angles, revealed a square-planar geometry around the metallic center for both compounds with the azide being linear. The theoretical infrared spectra of C₁ symmetry (electronic state ¹A) of the compounds are in agreement with the experimental data.     

Time-Dependent Cytotoxic Properties of Terpyridine-Based Copper Complexes

Five copper complexes supported by terpyridine ligands were prepared and characterized, viz. [Cu₃Cl₄(naphtpy)₂][CuCl₂] ( 1 ), [Cu₂Cl₂(naphtpy)₂](ClO₄)₂ ( 2 ), [CuCl₂(naphtpy)]₂(MeOH)₃(H₂O) ( 3 ), [CuCl₂(Cltpy)] ( 4 ) and [Cu(Cltpy)₂](ClO₄)₂ ( 5 ); (where naphtpy stands for 4’-((naphthalen-2-yl)methoxy)-2,2′:6′,2′′-terpyridine and Cltpy for 4′-chloro-2,2′:6′,2′′-terpyridine). Their ability to interact with DNA was investigated, and their cytotoxic behaviour was examined with three cells lines, namely human ovarian carcinoma cells (A2780), their derived cisplatin-resistant line (A2780cis), and human cervix adenocarcinoma cells (HeLa). All compounds show good cytotoxic properties (especially after 72 h of incubation). Remarkably, two compounds, 4 and 5 , are still almost inactive after 24 h (particularly 4 ), but are highly active after 72 h, with IC₅₀ values in the low-micromolar to sub-micromolar range. Compounds 1 and 2 induce necrosis, whereas late apoptosis is observed with 3 – 5 , 4 exhibiting a behaviour close to that of cisplatin.     

One mononuclear single-molecule magnet derived from Dy(III) and dmbpy (dmbpy = 4,4′-dimethyl-2,2′-dipyridyl)

Three β–diketonate mononuclear Ln-based compounds, formulated as [Tb^III(hfac)₃(dmbpy)](1), [Dy^III(hfac)₃(dmbpy)](2) and [Er^III(hfac)₃(dmbpy)](3) (hfac = hexafluoroacetylacetone, dmbpy = 4,4′-dimethyl-2,2′-dipyridyl) have been synthesized and structurally characterized by single crystal X-ray diffraction. Structure characterization reveals that complexes 1, 2 and 3 are isomorphous. Shape measurement shows the coordination geometry of complex 2 is trigonal dodecahedron (D_2d). Magnetic property study indicates complex 2 shows SIM behavior with observed frequency-dependent signals at low temperature.     

Determination of the Initiating Capability of Detonators Containing TKX‐50, MAD‐X1, PETNC,DAAF, RDX,HMX or PETN as a Base Charge,by Underwater Explosion Test

A comprehensive investigation to determine the initiation power of detonators containing as a base charge the novel explosives: dihydroxylammonium 5,5′‐bis(tetrazolate‐1N‐oxide) – TKX‐50, dihydroxylammonium 5,5′‐bis(3‐nitro‐1,2,4‐triazolate‐1N‐oxide) – MAD‐X1, pentaerythritol tetranitrocarbamate – PETNC and 3,3′‐diamino‐4,4′‐azoxyfurazan – DAAF in comparison with RDX, HMX and PETN was undertaken. In order to estimate the initiation power of the detonators, the underwater initiating capability test was used. The total energy as a sum of the primary shock wave energy and the bubble gas energy was determined for each of these explosives, by measuring the overpressure of the shock waves generated in water. Moreover, the complete synthesis for novel explosives is presented. The thermal behavior of the explosives was investigated using DSC (differential scanning calorimetry). The gas phase absolute molar enthalpies at 298 K and 10⁵ Pa were calculated theoretically using the modified complete basis set method (CBS‐4M; M referring to the use of minimal population localization) with the Gaussian 09 software. Gas phase standard molar enthalpies of formation (ΔH_f°_(g)) at 298 K were computed using the atomization energy method. Standard molar enthalpies of formation (▵H_(s)°) were calculated using ΔH_f°_(g) and the standard molar enthalpies of sublimation by applying Trouton’s rule. The Chapman‐Jouguet (CJ) characteristics based on calculated ▵H_(s)° values were computed using the EXPLO5 V6.01 thermochemical computer code. For the calculations the theoretical maximum densities and densities obtained during the experiments presented in this work were used.     

Chiral Molecular Clefts For Dicarboxylic Acid Complexation

Three efficient cleft-type receptors, 3,5 , and 6 have been prepared by attachment of two amidopyridine units as hydrogen bonding centers to either the 2,2′-positions of 9, 9′-spirobifluorene or the 6,6′-positions of 1,1′-binaphthyl spacers. The easy availability of these compounds in short synthetic routes make them attractive complexing agents for aliphatic and aromatic dicarboxylic acids which undergo bidentate binding in chloroform solution. ¹H NMR binding studies show that substrates of different size can be accommodated into the clefts and form 1:1 complexes that are predominantly stabilized by multiple host-guesthydrogen bonds. The flexible aliphatic substrates diethylmalonic, 2,2-diphenylsuccinic, glutaric, and pimelic acid form complexes with association constants K_a ranging from 10³ to 10⁴ L mol⁻¹. Significantly more stable complexes (K_a > 10⁵ L mol⁻¹) are obtained with the more rigid, preorganized substrate 5-dodecyloxyisophthalic acid.