NMR Spectral Investigations Research Articles

Improved Imide Receptors by Imprinting Using Pyrimidine-Based Fluorescent Reporter Monomers

[reaction: see text] Optically responsive receptors toward imides based on 6-substituted 2,4-bis(acrylamido)pyrimidines are presented. The monomers were readily prepared in good yield. Solution binding to 1-benzyluracil (BU) monitored by 1H NMR appeared lower than a previously reported pyridine-based monomer. However, as indicated by 1H NMR and IR spectral investigations, the association strength was demonstrated to be "masked" by dimerization of the pyrimidine-based monomer units. Thus, from dilution experiments, a dimerization constant of 731 M(-1) was estimated for the pyrimidine-based monomer 2,4-bis(acrylamido)-6-piperidinopyrimidine whereas for the pyridine-based monomer 2,6-bis(acrylamido)pyridine, no self-association was observed. This precluded an accurate determination of the binding constant for BU to the former monomer whereas for the latter a binding constant of 757 M(-1) was measured. Despite the strong self-association, the novel monomer was shown to lead to enhanced imprinting effects when compared to imprinted polymers prepared analogously, but using the pyridine-based monomer as the recognition element. This was attributed to a higher intrinsic binding affinity exhibited by the pyrimidine based host monomer vis a vis the guest and the existence in the former of more than one interaction site for the guest. The monomers exhibited fluorescence emission informative of the mode of monomer incorporation in the polymer and the presence of guest species. Thus, the fluorescence was rapidly and selectively quenched upon template addition, with the degree of quenching correlating with binding affinity and the amount of template bound to the polymer.

Equilibrium and structural studies on Co(II), Ni(II), Cu(II) and Zn(II) complexes with N-(2-benzimidazolyl)methyliminodiacetic acid: crystal structures of Ni(II) and Cu(II) complexes

Combined pH-metric, UV–Vis, 1H NMR and EPR spectral investigations on the complex formation of M(II) ions (M=Co, Ni, Cu and Zn) with N-(2-benzimidazolyl)methyliminodiacetic acid (H 2bzimida, hereafter H 2L) in aqueous solution at a fixed ionic strength, I=10 −1 mol dm −3, at 25 ± 1 °C indicate the formation of M(L), M(H −1L) − and M 2(H −1L) + complexes. Proton–ligand and metal–ligand constants and the complex formation equilibria have been elucidated. Solid complexes, [M(L)(H 2O) 2] · nH 2O ( n=1 for M = Co and Zn, n=2 for M = Ni) and {Cu (μ-L) · 4H 2O} n , have been isolated and characterized by elemental analysis, spectral, conductance and magnetic measurements and thermal studies. Structures of [Ni(L)(H 2O) 2] · 2H 2O and {Cu(μ-L) · 4H 2O} n have been determined by single crystal X-ray diffraction. The nickel(II) complex exists in a distorted octahedral environment in which the metal ion is coordinated by the two carboxylate O atoms, the amino-N atom of the iminodiacetate moiety and the pyridine type N-atom of the benzimidazole moiety. Two aqua O atoms function as fifth and sixth donor atoms. The copper(II) complex is made up of interpenetrating polymeric chains of antiferromagnetically coupled Cu(II) ions linked by carboxylato bridges in syn– anti (apical–equatorial) bonding mode and stabilized via interchain hydrogen bonds and π–π stacking interactions.

Non-template synthesis of ‘N 4’ di- and tetra-amide macrocylic ligands with variable ring sizes

Nine new macrocyclic ligands containing two- or four-amide groups have been prepared by the cyclization reaction of three different diamines with acid chlorides (oxalyl dichloride or malonyl dichloride), diesters (diethyl oxalate or diethyl malonate) or 1,2-dichloroethane. The macrocycles prepared are four tetraaza-14-crown-4, four tetraaza-15-crown-4 and one tetraaza-16-crown-4. All the macrocyclic ligands were characterized by elemental analysis and, IR, UV, NMR and mass spectral investigations.

Synthesis and characterization of [PEG400-alt-DEOS]/(δ-MgCl2)0.2597 complex

An alternating copolymer with the formula α-hydro-ω-oligo(oxyethylene)hydroxy poly[oligo(oxyethylene)oxydimethylsilylene] and a molecular weight of 9 860 was synthesized. Doping of this polymer with the extremely anhydrous salt δ-MgCl 2 resulted in a new magnesium complex with the formula poly[PEG400-alt-DEOS]/ (MgCl 2 ) 0.2597 . The structural hypothesis for the polymer was proposed on the basis of elemental analyses and molecular weight. Detailed 1 H, 13 C and 29 Si NMR spectral investigations fully confirmed the structure of poly[PEG400-alt-DEOS]. Mid-infrared FT-IR studies of the polymer showed that it presents 1) a sufficient number of terminal hydroxyl groups to confer a substantial degree of dissolution and salt-dissociation in the polymer complex; and 2) polyether fragments in a conformational geometry close to trans-gauche-trans. The conductivity against temperature plot for this very amorphous magnesium polymer complex demonstrated that the material conducts ionically by means of two types of charge- migration mechanisms.

NMR studies of transformations of aminoacid complexes of Pt(II) and Pd(II) in solution. 2. Bisalaninates

Synthetic procedures are suggested for diastereomers of Pt(II) and Pd(II) bischelates with alanine: cis- and trans-Pt(l-Ala)2 , trans-Pt(l-Ala)fd-Ala), trans-Pd(l-Ala)2 , and trans-Pd(l-Ala)(d-AIa). Methods of their isolation in individual solid state are proposed.1H,13C, and195Pt NMR spectral investigations are reported for the individual diastereomers and for M(Ala)2 racemates in DMSO solution. The trans-isomers of Pd(II) bisalaninates in DMSO solution are transformed into an equilibrium mixture of cis- and trans-isomers. For Pt(II) complexes, the cis ↔ trans equilibrium was also found but the equilibration rate is much lower than that for Pd(II) bischelates for both cis- and trans-isomer. An equilibrium 2M(l-Ala)(d-Ala) ⇌ M(l-Ala)2+M(d-Ala)2 is also shown to exist.

Synthetic and spectral investigations of fluorinated 4 H-1,4-benzothiazines and their conversion into sulfones

The synthesis of fluorinated 4 H-1,4-benzothiazines and their conversion into sulfones is reported. The fluorinated 4 H-1,4-benzothiazines were prepared by the condensation and oxidative cyclization of 2-amino-3-chloro-5-fluorobenzenethiol with compounds containing active methylene groups in DMSO. The reaction is believed to proceed via an enaminoketone system. Fluorinated 4 H-1,4-benzothiazine sulfones have been synthesized by the oxidation of fluorinated 4 H-1,4-benzothiazines by 30% hydrogen peroxide in glacial acetic acid. IR, NMR and mass spectral investigations are included.

Lanthanide(III) complexes with bidentate biheterocyclic ligands

Eight lanthanide thiocyanate complexes of the type [Ln(NCS) 3(PBH) 2] and [Ln(NCS) 3(MPB) 2], where Ln = La, Pr, Nd, Sm, Eu, Gd, Dy and Y and PBH and MPB are 2-(2-pyridylbenzimidazole) and 1-methyl-2-(2′-pyridyl)benzimidazole, respectively, have been synthesized and characterized by various physicochemical techniques such as conductance and thermogravimetric studies, electronic, IR, NMR ( 1H and 13C), EPR, CV and fluorescence spectral investigations. The v(CC) of the thiocyanate group indicates N coordination in all cases.

On the trans–cis controversy in Ti–TADDOLate-catalysed cycloadditions. Experimental indications for the structure of the reactive catalyst–substrate intermediate

In order to investigate the structure of the reactive intermediate in the titanium-catalysed 1,3-dipolar cycloaddition, a series of reactions catalysed by TiX(PriO)3 and TiX(PriO)-TADDOLate [X = Cl, Br, CF3SO3 (OTf)] complexes have been performed. The 1,3-dipolar cycloaddition between benzylidenephenylamine N-oxide and 3-[(E)-but-2′-enoyl]-1,3-oxazolidin-2-one is catalysed by 20 mol% TiCl(PriO)3 to give primarily the exo-isoxazolidine. If the chloride ligand of the catalyst is substituted with more bulky ligands such as bromide and trifluoromethanesulfonate, the selectivity of the reaction changes to give primarily the endo-isoxazolidine. The same change in diastereoselectivity from exo to endo is also observed by the application of TiX(PriO)-TADDOLate (X = Cl, Br, OTf) complexes as catalysts for the analogous reaction. On the basis of these results, NMR spectral investigations and MM2 models, the most reactive intermediate in the TiCl(PriO)3 catalysed cycloaddition is proposed to be an octahedral complex in which the chloride ligand is located in the axial position relative to the plane defined by the two carbonyl oxygen atoms from 3-[(E)-but-2′-enoyl]-1,3-oxazolidin-2-one and two alkoxide ligands. The structure of the reactive intermediate in the TiIV-TADDOLate-catalysed 1,3-dipolar cycloaddition and Diels–Alder reactions is also briefly discussed on the basis of the results obtained.

Interaction of anisole with 3α-hydroxy-5β-cholan-24-oic acid macrolides. Part 1. Comparative 1H NMR spectral investigation

Abstract 1 H NMR spectral investigation on the interaction of anisole (methoxybenzene) with five different (varying by ring size and substitution) cyclic 3α-hydroxy-5β-cholan-24-oic acid macrolides were performed. For 3α-hydroxy-5β-cholan-24-oic acid (lithocholic acid) macrolides (from triolide to pentolide) no effect was observed. In contrast, for 7α-trifluoroacetyloxy (7α-TFA) substituted lithocholate triolide obtained from chenodeoxycholic acid and for 12α-trifluoroacetyloxy (12α-TFA) substituted lithocholate triolide obtained from deoxycholic acid, clear site specific effects were observed. In the case of the 7α-TFA derivative, the aromatic guest causes the strongest up-field shift on the angular methyl 19 at the A/B ring junction of the steroid unit, and in 12α-TFA isomer the strongest effect is directed at the angular methyl 18 located at the C/D ring junction of the steroid skeleton. These findings are discussed in terms of steric factors and the size and flexibility of the cavity of the host molecule. Molecular mechanics is used in modeling the structures of three triolides.

Synthetic and spectral investigation of fluorinated phenothiazines and 4 H-1,4-benzothiazines as potent anticancer agents

The syntheses of fluorinated phenothiazines and fluorinated 1,4-benzothiazines are reported.Fluorinated phenothiazines have been prepared via a Smiles rearrangement of N-formylateddiphenylsulphides, synthesized in turn by condensation of substituted 2-aminobenzenethiolswith 2-chloro-5-trifluoromethylnitrobenzene followed by formylation with formic acid.Fluorinated 4 H-1,4-benzothiazines have been prepared by the condensation and oxidativecyclization of substituted 2-aminobenzenethiols with p-fluorobenzoylacetone in DMSO.The reaction is believed to proceed via an enaminoketone system. IR and NMR spectralinvestigations are included.

A physicochemical study on organic eutectics and addition compound; benzidine–pyrogallol system

The phase diagrams of the binary organic system of benzidine–pyrogallol was determined by the thaw–melt method. The solidification behaviour of the pure components, their eutectics, and the addition compound were studied by measuring the movement of growth front in a capillary. From the data on X-ray diffraction, thermal and microscopic investigations it can be inferred that the eutectics are not simple mechanical mixtures of the components involved. The IR and NMR spectral investigations were carried out to throw light on the nature of bonding between the two components forming the addition compound.

Some physicochemical studies on organic eutectics and 1:2 addition compound; benzidine-β-naphthol system

With a view to elucidating the chemistry of the benzidine-β-naphthol system, its phase diagram was determined by the thaw-melt method. The solidification behaviour of the pure components, the eutectics and the addition compound was studied at different degrees of supercooling by the capillary method. From the data obtained by X-ray diffraction, thermal and microscopic studies, it can be inferred that the eutectics are not simple mechanical mixtures of the components involved. Infrared and NMR spectral investigations were carried out to clarify the nature of bonding between the two components forming the addition compound.

Carbon‐13 NMR spectral investigations on allenic esters: Rationalization of carbon‐13 NMR chemical shifts and relaxation times (T1)

AbstractCarbon‐13 NMR chemical shifts (CDCl3 and C6D6 solvents) and relaxation times (T1) were determined for carbons in a series of allenic esters [RR1CCCHCO2 Et; (1) R = R1 = H; (2) R = H, R1 = CH3; (3) R = H, R1 = CH3CH2; (4) R = R1 = CH3; (5) R = CH3, R1 = CH3CH2]. A comparison of the experimental δ13C values with those obtained by semi‐empirical additivity relationships revealed the inadequacy of these relationships to explain the obtained results. A rationalization of δ13C and relaxation time data is offered, inter alia, in terms of rotameric conformational preferences of the ester function.

Carbon‐13 NMR spectral investigation of organosulfur compounds. Substitutent‐induced chemical shift (SCS) effects in acyclic saturated organosulfur compounds

AbstractThe 13C NMR shielding effects on proximal carbon atoms caused by oxidation of sulfenyl sulfur to sulfinyl, sulfonyl and sulfonium species are diagnostic indicators and extremely useful in the structural characterization of organosulfur compounds.

Regio- and stereo-selectivity in uncatalysed and catalysed Diels–Alder reactions of allenic esters with furan and 2-methylfuran

Complete regio- and stereo-selectivity in both uncatalysed and catalysedt Diels–Alder additions of furan to the allenic esters (1a–e), and of 2-methylfuran to the allenic esters (1b, c) has been determined through detailed 1H and 13C NMR spectral investigations. Eu(fod)3 and Pr(fod)3 have been found to be very useful mild Lewis acid catalysts for these cycloadditions; several mol % of these reagents significantly enhance the selectivity and yield of these reactions without adversely affecting the fragile functionalities. A rationalization of the observed regio- and stereoselectivity and reactivity profile, based on the stereoelectronic factors operating in the transition states is given.

Chemical and x-ray structural investigation of a new diterpene lactone betolide

A crystalline substance with the composition C20H24O5 has been isolated from the roots of common betony. The spatial structure of this new diterpene lactone, betolide, has been established from the results of UV, IR, NMR, and13C NMR spectral and x-ray structural investigations — 13-formyl-14-hydroxy-(2′-hydroxy-5′-oxotetrahydrofuro) [3′,4′:11,12′]-Δ8,10,12-podocarpane, the first representative of new tetracyclic diterpenes the lactone ring of which is formed with the participation of a hydroxyl of a geminal diol. The stability of a lactone ring of this type and a high reactivity of the semiacetal hydroxyl have been shown.

METAL COMPLEXES OF THE TETRAETHYLESTER OF 4-(2-HYDROXY-PHENYL-AMINO)-1,3-BUTADIENE-1,3-DIPHOSPHONIC ACID AND THE LIQUID PHASE OXIDATION OF CUMENE IN THEIR PRESENCE

Abstract The tetraethylester of 4-(2-hydroxy-phenylamino)-1,3-butadiene-1,3-diphosphonic acid 3 and its zinc and cobalt complexes (3-Zn, 3-Co) have been synthesized and their structures were determined by IR, 1H-NMR, 31P {1H}-NMR and 13C-NMR spectral investigations. The effect of these compounds on the liquid phase oxidation of cumene is studied and compared with that of 2-aminophenol 2 and its metal complexes 2-M. It is found that the ligand 3 shows the strongest inhibiting effect, while 3-Co, 3-Zn and 2-Co accelerate the oxidation process.

Synthesis and carbon‐13 nuclear magnetic resonance spectroscopy of 5,6‐dihydro‐2‐methyl‐1,4‐oxathiin, trans‐tetrahydro‐1,4‐benzoxathiin, 1,4‐tetrahydro‐[9,10]benzoxathiin, the 4‐oxides, 4,4‐dioxides and related acyclic compounds

AbstractThe results of a 13C NMR spectral investigation involving 5,6‐dihydro‐1,4‐oxathiins, 1,4‐tetrahydro[9,10]benzoxathiin, trans‐tetrahydro‐1,4‐benzoxathiin, and the corresponding sulfoxides and sulfones are reported. An interpretation involving a dipolar structure with (2p→2p)π conjugation as opposed to (2p→3d)π interactions with the vinyloxy sulfides seems consistent with trends in the 13C NMR shifts. For the sulfoxides and sulfones, the substitutent‐induced chemical shift (SCS) effects at the β vinylic carbons (βSO and βSO2 effects) are considerably less than those at sp3 carbons. The γSO and γSO2 values at the sp2γ carbons indicate deshielding, in contrast to the shielding at the sp3 carbons.

Comparison of organo-nickel(II), -palladium(II) and -platinum(II) complexes : I. Preparation and acidities of cationic methyl(methoxy)carbene complexes

α-Methoxyvinylmetal(II) complexes of the type trans-C 6Cl 5M(PPhMe 2) 2C(OMe)CH 2 (abbr. [M]C(OMe)CH 2, where M = Ni, Pd, Pt) were prepared by the reaction of [M]Cl and LiC(OMe)=CH 2, and were treated with perchloric acid to give cationic methyl(methoxy)carbene complexes, [M] +C(OMe)Me, ClO 4 −. Ethynylmetal(II) complexes, [M]CCH, were prepared by the reaction of [M]Cl, silver perchlorate and HCCH in the presence of triethylamine, and were treated with perchloric acid in the presence of methanol to give either [M] +C(OMe)Me, ClO 4 −(M = Ni, Pt) or [Pd] +OH 2, ClO 4 −. The relative Br∅nsted acidity of [M] +C(OMe)Me was found to be in the order M = Ni<Pd>Pt. From the IR, 1H NMR and 13C NMR spectral investigations, the order was explained in terms of the largest σ-bonding polarity for Ni in the MC bond of [M]C(OMe)CH 2 and the largest back π-donor ability for Pt in the MC bond of [M] +C(OMe)Me.

ChemInform Abstract: A (7)LI NMR SPECTRAL INVESTIGATION OF GROUP III AND IV METALATES IN ETHER SOLVENTS

Chemischer InformationsdienstVolume 6, Issue 20 Physical Organic Chemistry ChemInform Abstract: A (7)LI NMR SPECTRAL INVESTIGATION OF GROUP III AND IV METALATES IN ETHER SOLVENTS R. J. HOGAN, R. J. HOGANSearch for more papers by this authorP. A. SCHERR, P. A. SCHERRSearch for more papers by this authorA. T. WEIBEL, A. T. WEIBELSearch for more papers by this authorJ. P. OLIVER, J. P. OLIVERSearch for more papers by this author R. J. HOGAN, R. J. HOGANSearch for more papers by this authorP. A. SCHERR, P. A. SCHERRSearch for more papers by this authorA. T. WEIBEL, A. T. WEIBELSearch for more papers by this authorJ. P. OLIVER, J. P. OLIVERSearch for more papers by this author First published: May 20, 1975 https://doi.org/10.1002/chin.197520068AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume6, Issue20May 20, 1975 RelatedInformation