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By the reaction of para-formylcalix[4]arenes 1–6 with trialkyl phosphites in the presence of dry hydrogen chloride, calix[4]arenes 7–13 possessing dialkylphosphoryl-hydroxymethyl groupings at the upper rim were synthesized. Calix[4]arenes 18–23 functionalized with dialkylphosphoryl-alkyl(aryl)aminomethyl groups were obtained by sodium-promoted addition of dialkyl phosphites to C=N bonds of para-iminocalix[4]arenes 14–17. The consecutive treatment of α-hydroxy- or α-aminophosphonic acid dialkyl esters of calix[4]arenes 7, 10, 18, and 21 with bromotrimethylsilane and methanol gave dihydroxyphosphoryl derivatives of calix[4]arenes 24–27. It was shown that calix[4]arenes bearing at the macrocyclic upper rim hydroxymethylphosphonic fragments, as well as bis-hydroxymethyl(aminomethyl)phosphonic fragments, are able to undergo self-assembly with formation of dimeric OH···O=P hydrogen bonded associates. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:58–67, 2001

In this article we shall review the salient aspects concerning the syntheses, characterization, and complexing properties of variously substituted mono- and bis-(α-amino)- and (α-hydroxy)-phosphonates. Characterization of these compounds was mainly achieved by 1H, 13C, and 31P NMR spectroscopy, by FABMS techniques, and by X-ray diffraction analyses. Hydrolytic cleavage in alkaline solutions of the dialkyl esters gave the corresponding monoesters, which also show good complexing properties toward standard metals and lanthanides. The last section of this article is dedicated to a review of the synthesis, characterization and stereochemistry of cyclophanes, and macrocyclic compounds possessing phosphonate units. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:493–504, 2000

The enantiomers of 17 α-hydroxybenzylphosphonate diethylesters containing para, or ortho substituents or other aromatic rings (1-naphthyl, 2-naphthyl, and 2-thienyl) have been successfully separated by HPLC on a Whelk-O 1 chiral stationary phase which is superior to other CSPs. The effect of the substituents, particularly halogens, on the enantioselectivity was investigated and related to a chiral recognition model. The absolute configurations of 4-methyl and 2-methyl substituted α-hydroxybenzylphosphonates were obtained by measurement of the circular dichroism spectra of the isolated enantiomers. Chirality 10:100–105, 1998. © 1998 Wiley-Liss,Inc.

The synthesis and NMR characterization of some poly(ether ketone)/poly(ether sulfone) (PEK/PES) alternating copolymers together with a series of sequential homopolymers containing CO, O, S and SO 2 bridging groups, all obtained by electrophilic condensation reactions using phosphorus pentoxide/methanesulfonic acid as dehydrating agent, is here reported. Properties of such polymers are compared with those of their model compounds from which it can be inferred that both proton and carbon chemical shifts are very sensitive to the electronic environment generated by the O, S, CO and SO 2 bridges. Differential scanning calorimetry indicates that our polymers are essentially amorphous irrespective of the bridging sequence. From viscosity measurements the molecular weights of these copolymers are judged to be very low.

Variable-temperature 31P NMR spectroscopy was used to extract Arrhenius and Eyring parameters of the hindered rotation about amide bonds in an acylated aminophosphonate. The results permit the differentiation between stepwise or concerted rotation.

The differences in complexation behaviour of two diastereomeric tetraazamacrocycles, meso (1) and racemic (2) 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, are explained by different conformations in solution, 1 being one stable conformer of almost rigid structure while 2 shows higher conformational flexibility to avoid steric strain. The methods used were 1H and 13C NMR and molecular modelling.

New poly(aryl ether ketone) and poly(aryl ether sulfone) monodisperse model oligomers were synthesized in good yield via nucleophilic reactions. They were characterized by means of 1 H and 13 C NMR spectroscopy, and all chemical shifts were assigned to the corresponding nuclei. Both proton and carbon chemical shifts are very sensitive to the electronic environment generated by the O, CO and SO 2 bridges, but in all oligomers, nuclei with similar electronic environments are very close to each other no matter what the sequence or the length of the oligomer is. Only quaternary carbons are more sensitive to the nature of the bridging groups, and therefore their chemical shifts can be of utility in sequencing the polymers

Partial resolution of the title compound 2 into its optical antipodes was achieved by enantioselective chromatography on triacetylcellulose. The absolute configuration of the enantiomers has been tentatively assigned on the basis of their CD spectra. Empirical force-field calculations were performed to characterize the minimum energy conformers of 2 and it was found that the two C2 symmetrical isomers are ca. 3.7 kcal mol–1(15.5 kJ mol–1) more stable than those of Ci and C1 symmetry. Calculated geometrical parameters of one C2 symmetrical conformer of 2 are in good agreement with those found by single-crystal X-ray analysis of the N,N′-ditosylparacyclophane precursor 1. The barrier to racemization has been estimated to be >35 kcal mol–1(> 146.5 kJ mol–1).

Variously substituted amino aryl-methyl-diphosphonate ethyl esters have been prepared in good yields by adding diethyl phosphonate to the corresponding Schiff bases. All compounds were characterized by NMR and MS-FAB techniques, which reveal the presence of peaks or fragmentation patterns very useful and diagnostic for constitutional assignment. Evidences for a stereospecific addition of diethyl phosphonate to the two—CH·N—sites in diaryl diimines have been observed. The presence of heteroaromatic rings such as pyridine or azo-groups renders such compounds also very attractive for complexation studies towards metals; thus, these molecules are for potential uses in agrochemistry and biodiagnostic medicine.

The phosphorylated calix[4]arenoid para- and meta-substituted cyclophane tetramers, which were synthesised in good yields starting from parent cyclic hydrocarbons, show a 'saddle-shaped' rigid conformation in solution, and the methylenephosphonic acid dialkyl ester groups are in a strategic position for complexation with neutral guests.

By the reaction of para-formylcalix[4]arenes 1–6 with trialkyl phosphites in the presence of dry hydrogen chloride, calix[4]arenes 7–13 possessing dialkylphosphoryl-hydroxymethyl groupings at the upper rim were synthesized. Calix[4]arenes 18–23 functionalized with dialkylphosphoryl-alkyl(aryl)aminomethyl groups were obtained by sodium-promoted addition of dialkyl phosphites to C=N bonds of para-iminocalix[4]arenes 14–17. The consecutive treatment of α-hydroxy- or α-aminophosphonic acid dialkyl esters of calix[4]arenes 7, 10, 18, and 21 with bromotrimethylsilane and methanol gave dihydroxyphosphoryl derivatives of calix[4]arenes 24–27. It was shown that calix[4]arenes bearing at the macrocyclic upper rim hydroxymethylphosphonic fragments, as well as bis-hydroxymethyl(aminomethyl)phosphonic fragments, are able to undergo self-assembly with formation of dimeric OH···O=P hydrogen bonded associates. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:58–67, 2001

We present the new host molecule 1 which binds basic amino acid esters in water. It recognizes both positively charged groups of the amino acid esters by electrostatic and hydrogen bond interaction...

We have synthetized medium-sized cyclophanes and macrocycles containing phosphonic groups, directly linked to the aromatic rings of the phanes or as pendant arms, for use as specific receptors for the selective complexation of neutral guests or for complexing lanthanides, as luminescent sensors and for diagnostic bioassays in medicine. Furthermore, because it would be of great interest for biochemistry as well as for pharmacological studies to dispose of preorganized rigid chiral hosts for biorelevant molecules we designed inter alia , some new chiral macrocycles capable of a triple binding mode and we used them for constructing macrocycles that could also be of interest for chiral recognition and chiral separations. Thus, in this paper we shall review the salient aspects of some macrocycles synthetized in our laboratory, all possessing the phosphonate moiety and a spirobisindanol scaffold and able to act as complexing agents for cations and organic substrates. In particular, we shall describe their NMR characterization, their stereochemistry in solution and in the solid state, and their use as chiral receptors for biorelevant molecules. Chiral HPLC resolution of some of them is also reported.

The complete assignment of the proton and carbon spectra for two new 2-pyridylquinoline ligands, 4-phenyl-2-(2′-pyridyl)quinoline (Ph-pq) and 2,6-di(4′-phenylquinol-2′-yl)pyridine (Ph-dqp), and their ruthenium(II) complexes [Ru(bpy)2(Ph-pq)](PF6)2 and [Ru(Ph-dqp)2](PF6)2 has been accomplished using a combination of one- and two-dimensional NMR techniques, including COSY, NOESY, one-bond and long-range HETCOR and selective INEPT spectra. The J(H,H) and J(C,H) values have been determined for the majority of the resonances.

A series of polyamides and polyureas containing cyclic (1b, 1c, and 1d) or acyclic (2b, 2c, and 2d) bipyridinediyl diamino units in the polymer backbone were prepared. By introducing aliphatic or aromatic comonomers, it was possible to influence the degree of rigidity of the resulting polymers. In the synthesis of the polymers 2c and 2d two new azamacrocycles 5 and 6, respectively, were also produced and they were isolated and characterized. 1H-NMR and IR spectral data support the structure of the synthesized compounds. Thermal analysis data indicate that the polyureas posses lower PDT (polymer degradation temperature) values with respect to the corresponding polyamides.

We present here a new class of cleft-like receptor molecules containing two or four phosphonates anions, tailored for multipoint binding of their substrates. Depending on the accessibility of the cleft, these hosts are water soluble and selective for short or long f , y -diammonium compounds. Due to their inherent chirality, we found that only those host-guest combinations which allow a three-point-interaction were effective.

The synthesis, as well as the stereochemical and solid-state structure characterization of a novel sterically congested cleft-like receptor molecule, fully equipped for multipoint recognition and containing a chiral spirobiindanol phosphonate unit, is reported.

The synthesis of two novel polyamide ligands 3 and 4, containing 2,17-diaza[3.3](6,6′)-2,2′-bipyridinophane or 6,6′-bis(2-picolylaminomethyl)-2,2′-bipyridine units as part of the polymer backbone, respectively, and of the appropriate diamide model compounds 1c and 2c is described. 1H-NMR and IR spectral data support the ligand structures; furthermore, 1H-VTNMR analysis on macrocyclic diamide 1c indicates a restricted rotation of the amide bonds at ambient temperature and suggests for this molecule a fixed syn conformation in solution, with a “face to face” arrangement of the dipyridinyl moieties. Model compound 2c and polyamide 4 form stable 1:1 complexes with transition metals Co(II), Ni(II), and Cu(II). Conversely, macrocyclic model 1c and polyamide 3 exhibit the unique property to specifically complex Cu(II), even in the presence of sizeable amounts of Co(II) and Ni(II). The IR spectral changes related to the ligands upon complexation are briefly discussed.

A number of alternating copolymers containing anthryl and aryl units in the polymer chain have been prepared by Friedel-Crafts arylation of the anthracene (polymer type B) or by condensation of 9,10-bis(chloromethyl) anthracene with opportune aromatic substrates (polymer type A). Polymers of type A were all found to contain 9,10-disubstituted anthracene units, but polymers of type B were found to contain 1,4-disubstituted anthracene units. Structure of the polymers were established through their NMR and ultraviolet spectra, and through analogy with appropriate model compounds. It has been found that the inclusion of anthracene units in the polymer chain yields higher melting and more soluble materials with respect to polybenzyls containing only aryl units. Anthracene units introduce, also, some interesting fluorescence characteristics in the polymers, which show intense emission at about 440 mμ.

The polycondensation reactions of benzyl chloride, α-chloroethylbenzene, and benzhydryl chloride in the presence of SnCl4 or AlCl3 as catalysts have been investigated in the temperature range between +80° and −135°C. Polycondensations of benzyl chloride and α-chloroethylbenzene are quite similar in the reaction kinetics and are thought to occur by the same displacement mechanism. Polycondensation of benzhydryl chloride, however, seems to involve the formation of benzhydryl carbonium ions. At low temperatures linear polymers tend to be formed, in contrast with branched polymers produced at room temperature. Steric effects are found to play a major role in protecting polymers from branching at lower temperatures. Polybenzyl polymers are found to be less linear than poly(-α-methylbenzyl), even when prepared at −135°C.

The conformational equilibria of piperidine diamides derived from five cyclic 1,2-dicarboxylic acids (I–V) have been investigated by dipole moment measurements and a priori conformational energy estimates. Since these diamides represent the building blocks of the polyamides derived from the above cyclic diacids and piperazine or trans-2,5-dimethylpiperazine, the results obtained in the study of the models have been used to investigate the conformation of the polymers. The overall evidence suggests that cyclopentane, cyclohexane, and bicyclooctane piperazine polymers behave as rigid rods in which the structural units possess approximately the same conformational preference exhibited by the respective model diamides.

Carbon-13 n.m.r. chemical shifts for 8 anisoles and 15 diphenyl ethers are reported. para-Carbon shieldings are found to be sensitive to the degree of steric interference to conjugative electron re...

Synthese de composes crowns azotes, d'azacyclophanes et d'azapyridinophanes par couplage de precurseurs bis-[halomethyl] ou bis-[tosylate esters] avec le tosylamidure de sodium