Lanthanide Complexes of Polyacid Ligands derived from 2, 6-bis(pyrazol-1-yl)pyridine,pyrazine, and 6, 6′-bis(pyrazol-1-yl)-2, 2′-bipyridine: Synthesis and luminescence properties

The synthesis of three novel pyrazole-containing complexing acids, N,N,N′,N′-{2, 6-bis[3-(aminomethyl)pyrazol-1-yl]-4-methoxypyridine}tetrakis(acetic acid)( 1 ), N,N,N′,N′-{2, 6-bis[3-(aminomethyl)pyrazol-1-yl]pyrazine}-tetrakis(acetic acid) ( 2 ), and N,N,N′,N′-{6, 6′-bis[3-(aminomethyl)pyrazol-1-yl]-2, 2′-bipyridine}tetrakis(acetic acid) ( 3 ) is described. Ligands 1–3 formed stable complexes with Eu^III, Tb^III, Sm^III, and Dy^III in H₂O whose relative luminescence yields, triplet-state energies, and emission decay lifetimes were measured. The number of H₂O molecules in the first coordination sphere of the lanthanide ion were also determined. Comparison of data from the Eu^III and Tb^III complexes of 1–3 and those of the parent trisheterocycle N,N,N′,N′-{2, 6-bis[3-(aminomethyl)pyrazol-l-yl]pyridine}tetrakis(acetic acid) showed that the modification of the pyridine ring for pyrazine or 2, 2′-bipyridine strongly modify the luminescence properties of the complexes. MeO Substitution at C(4) of 1 maintain the excellent properties described for the parent compound and give an additional functional group that will serve for attaching the label to biomolecules in bioaffinity applications.     

Syntheses and molecular self-assembly of chiral phosphorami-dates

Two chiral phosphoramidates,(R)-(-)-1,1'-binaphthyl-2,2'-dihydroxy-N-[α-(S)-methylbenzyl] phosphoramidate and (-)-1,1'-biphenyl-2,2'-dihydroxy-N-[α-(S)-methylbenzyl]-phosphoramidate were synthesized.Their crystal structures were determined by X-ray single crystal diffraction analysis.The phosphoramidate molecules are self-associated by inter-molecular N-H...O = P hydrogen bonds and aromatic edge to face interactions.     

脱铁伴清蛋白两结合位点不同酪氨酸氢键的特性

The interaction of gallium（Ⅲ） with the ligands containing phenolic group（s）, such as salicylic acid, 8-hydroxyquinoline, N,N＇-bis（2-hydroxybenzyl）ethylenediamine-N,N＇diacetic acid （HBED）, N,N＇-ethylenebis[2-（o- hydroxyphenyl）glycine （EHPG）, and ovotransferrin, was studied, respectively, by means of fluorescence in 0.01 mol/L Hepes at pH 7.4 and room temperature. Fluorescence intensity showed an increase when gallium（Ⅲ） was bound to 8-hydroxyquinoline and HBED. In contrast, it was decreased with the interaction of gallium（Ⅲ） with salicylic acid and EHPG. At pH 7.4, there was N…H-O type intramolecular hydrogen bond in the former, and the latter existed O…H-O type intramolecular hydrogen bond. Fluorescence titration of apoovotransferrin with gallium（Ⅲ） displayed that the fluorescence intensity was decreased at the N-terminal binding site, while enhanced at the C-terminal binding site. It can account for the O…H-O type intramolecular hydrogen bonds for the phenolic groups of Tyr92 and Tyr191 residues at the N-terminal binding site. And there are N…H-O type intramolecular hydrogen bonds for Tyr431 and Tyr524 residues at the C-terminal binding site. In addition, under the same conditions, the conditional binding constant of gallium（Ⅲ） with EHPG or HBED determined by fluorescence method is lg KGa-EHPG=19.18 or lg KGa-HBED= 19.08.     

Intramolecular cyclization of 1,3-diamino-2-hydroxypropan-N,N,N´,N´-tetrakis(methylphosphonic acid) upon phosphonomethylation of 1,3-diaminopropan-2-ol

Phosphonomethylation of 1,3-diaminopropan-2-ol affords the mixture of 1,3-diamino-2-hydroxypropan-N,N,N´,N´-tetrakis(methylphosphonic acid) (1) with its cyclic ether, viz., [(6-[bis(phosphonomethyl)amino]methyl-2-hydroxy-2-oxido-1,4,2-oxazaphosphinan-4-yl)methyl]phosphonic acid (2), but not 1, as assumed earlier.

     

Synthesis and Temperature‐Induced Morphological Control in a Hybrid Porous Iron–Phosphonate Nanomaterial and Its Excellent Catalytic Activity in the Synthesis of Benzimidazoles

A new organic–inorganic hybrid porous iron–phosphonate material, HPFP‐1, has been synthesized under hydrothermal conditions by using hexamethylenediamine‐N,N,N′,N′‐tetrakis‐(methylphosphonic acid) (HDTMP) as the organophosphorus precursor. The morphology of this material was found to be different at three different temperatures. The material that was synthesized at 453 K showed a flake‐like particle morphology and the material was highly crystalline. Whereas, the materials that were synthesized at 443 K and 423 K were semi‐crystalline and showed rod‐like‐ and spherical morphological features, respectively. SEM and TEM were employed to understand this change in particle morphology depending on the reaction temperature. Powder XRD analysis suggested the formation of a new tetragonal phase in HPFP‐1 (a=11.313, c=15.825 Å; V=2025.659 ų). N₂‐sorption analysis suggested the existence of supermicropores and interparticle mesopores in these materials. Elemental‐ and thermal analyses, as well as FTIR spectroscopy, were employed to verify the composition and framework bonding of the material. The HPFP‐1 material showed excellent catalytic activity for the synthesis of benzimidazole derivatives under mild liquid‐phase reaction conditions.     

Engineered C–N Lyase: Enantioselective Synthesis of Chiral Synthons for Artificial Dipeptide Sweeteners

Aspartic acid derivatives with branched N‐alkyl or N‐arylalkyl substituents are valuable precursors to artificial dipeptide sweeteners such as neotame and advantame. The development of a biocatalyst to synthesize these compounds in a single asymmetric step is an as yet unmet challenge. Reported here is an enantioselective biocatalytic synthesis of various difficult N‐substituted aspartic acids, including N‐(3,3‐dimethylbutyl)‐l ‐aspartic acid and N‐[3‐(3‐hydroxy‐4‐methoxyphenyl)propyl]‐l ‐aspartic acid, precursors to neotame and advantame, respectively, using an engineered variant of ethylenediamine‐N,N′‐disuccinic acid (EDDS) lyase from Chelativorans sp. BNC1. This engineered C–N lyase (mutant D290M/Y320M) displayed a remarkable 1140‐fold increase in activity for the selective hydroamination of fumarate compared to that of the wild‐type enzyme. These results present new opportunities to develop practical multienzymatic processes for the more sustainable and step‐economic synthesis of an important class of food additives.     

DFT study of the structure and property of small organic hole‐transporting molecules

In this article, all calculations are performed at B3LYP/6‐31G** level. For each one of the molecule, including triphenylamine (TPA), N,N′‐diphenyl‐N,N′‐bis(3‐methyllphenyl)‐(1,1′‐biphenyl)‐4,4′‐diamine (TPD), biphenyl (Bp), and their derivatives (TPAs, TPDs, Bps, respectively), the geometry is optimized for both neutral and radical‐cation states. Their reorganization energy is then compared. It seems that it is the monomer, TPAs, and not the central biphenyl moiety that determines the properties of TPDs. However, this is contradictory of some previous results. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

N,N′‐Bis(2‐pyridylmeth­yl)ferrocene‐1,1′‐diyldicarboxamide and N,N′‐bis­(3‐pyridylmeth­yl)ferrocene‐1,1′‐diyldicarboxamide

The mol­ecules of N,N′‐bis­(2‐pyridylmeth­yl)ferrocene‐1,1′‐diyl­dicarboxamide, [Fe(C₁₂H₁₁N₂O)₂], contain intra­molecular N—H⋯N hydrogen bonds and are linked into sheets by three independent C—H⋯O hydrogen bonds. The mol­ecules of the isomeric compound N,N′‐bis­(3‐pyridylmeth­yl)ferrocene‐1,1′‐diyldicarboxamide lie across inversion centres, and the mol­ecules are linked into sheets by a combination of N—H⋯N hydrogen bonds and π–π stacking inter­actions between pyridyl groups.     

The Stability of Metal N,N,N′,N′‐Tetrakis(2‐aminoethyl)ethane‐ 1,2‐diamine (=penten) Complexes and the X‐Ray Crystal Structure of [Tl(NO3)(penten)](NO3)2

Complex formation between N,N,N′,N′‐tetrakis(2‐aminoethyl)ethane‐1,2‐diamine (penten) and the metal ions Mn²⁺, Co²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Ag⁺, Pb²⁺, and Tl³⁺ (in 1.00M NaNO₃ and 25°) was investigated by potentiometry and spectrophotometry. These are the first reported values of the stability constants for this ligand with Ag⁺, Pb²⁺, and Tl³⁺. The X‐ray crystal structure of [Tl(NO₃)(penten)](NO₃)₂ was determined. In this structure, Tl³⁺ shows a coordination number of seven made up of the six N‐donors and one O‐atom of NO.     

Synthesis of Some Novel Amino Phenols with Octahydro‐1,1′‐binaphthyl Backbone

A series of new octahydro‐1,1′‐binaphthyl derivatives, namely (R)‐(+)‐2‐(N, N‐dialkylamino)‐2′‐hydroxy‐5,5′,6,6′,7, 7′,8,8′‐octahydro‐1,1′‐binaphthyls (7,9), have been synthesized. Their asymmetric induction for enantioselective addition of Et₂Zn to benzaldehyde was examined and it was found that (R)‐(+)‐2‐(N‐cyclohexyl‐N‐methylamino)‐2′‐hydroxy‐5, 5′,6,6′,7,7′,8,8′‐octahydro‐1,1′‐binaphthyl (9c) exhibited the best asymmetric induction among the ligands prepared, up to 55% ee of 1‐phenylpropanol being obtained.     

Synthesis and Crystal Structure of Peptide‐2,2′‐Biphenyl Hybrids

1,1′‐Biphenyl derivatives with amino acid/peptide substitution at C(2) and C(2′) (‘peptide‐biphenyl hybrids', 6 – 8 ) have been prepared by direct N‐acylation of amino acid/peptide derivatives with 1,1′‐biphenyl‐2,2′‐dicarbonyl dichloride ( 5 ). Both conformers, which arise from the rotation around the aryl aryl bond, have been detected by ¹H‐NMR spectroscopy. Single atropisomers of each 6 ((R)‐configuration at the stereogenic axis) and 7 ((S)‐configuration at the stereogenic axis) have been obtained in quantitative yield by slow evaporation of methanolic solutions. The procedures are dynamic atropselective resolutions (asymmetric transformations of the second kind). The crystal structures of the peptide‐biphenyl hybrids 6 and 7 show highly ordered molecular and supramolecular structures with extensive intramolecular and intermolecular H‐bonding.     

One‐dimensional C—H...N hydrogen‐bonded polymers in flexible tetrapyridyl systems

In N,N,N′,N′‐tetrakis(2‐pyridylmethyl)propane‐1,3‐diamine, C₂₇H₃₀N₆, (I), and N,N,N′,N′‐tetrakis(2‐pyridylmethyl)butane‐1,4‐diamine, C₂₈H₃₂N₆, (II), the twofold rotational symmetry of (I) favours the formation of a one‐dimensional hydrogen‐bonded polymer with two columns of C—H...N hydrogen bonds, while the inversion symmetry of (II) allows the formation of a one‐dimensional hydrogen‐bonded polymer stabilized by four columns of C—H...N hydrogen bonds. The possible role played by the chain length of the linking alkanediamine in determining the type of supramolecular architecture in this series of compounds is discussed.     

Polymeric Colorants: Statistical Copolymers of Indigo Building Blocks with Defined Structures

Statistical copolymers of indigo ( 1a ) and N‐acetylindigo ( 1b ) building blocks with defined structures were studied. They belong to the class of polymeric colorants. The polymers consist of 5,5′‐connected indigo units with keto structure and N‐acetylindigo units with uncommon tautomeric indoxyl/indolone (=1H‐indol‐3‐ol/3H‐indol‐3‐one) structure (see 2a and 2b in Fig. 1). They formed amorphous salts of elongated monomer lengths as compared to monomeric indigo. The polymers were studied by various spectroscopic and physico‐chemical methods in solid state and in solution. As shown by small‐angle‐neutron scattering (SANS) and transmission‐electron microscopy (TEM), disk‐like polymeric aggregates were present in concentrated solutions (DMSO and aq. NaOH soln.). Their thickness and radii were determined to be ca. 0.4 and ca. 80 nm, respectively. From the disk volumes and by a Guinier analysis, the molecular masses of the aggregates were calculated, which were in good agreement with each other. Defined structural changes of the polymer chains were observed during several‐weeks storage in concentrated DMSO solutions. The original keto structure of the unsubstituted indigo building blocks reverted to the more flexible indoxyl/indolone structure. The new polymers were simultaneously stabilized by intermolecular H‐bonds to give aggregates, preferentially dimers. Both aggregation and tautomerization were reversible upon dissolution. The polymers were synthesized by repeated oxidative coupling of 1,1′‐diacetyl‐3,3′‐dihydroxybis‐indoles 5 (from 1,1′‐diacetyl‐3,3′‐bis(acetyloxy)bis‐indoles 6 ) followed by gradual hydrolysis of the primarily formed poly(N,N′‐diacetylindigos) 7 (Scheme). N,N′‐Diacetylbis‐anthranilic acids 9 were isolated as by‐products.     

Derivatives of 2,3‐dihydroimidazo[1,5,4‐ef][1,2,5]‐benzothiadiazepin‐6(4h,7h)‐thione 1,1‐dioxide,a new heterocyclic system related to tibo

The synthesis of derivatives of 2,3‐dihydroimidazo[1,5,4‐ef][1,2,5]benzothiadiazepin‐6(4H,7H)‐thione 1,1‐dioxide is reported starting from N‐substituted ethyl 2‐(5‐chloro‐2‐nitrobenzenesulfonamido)‐2‐alkyl‐acetates. Fundamental steps of the synthetic pathway were: i) intramolecular cyclization of N‐substituted 2‐(2‐amino‐5‐chlorobenzenesulfonamido)‐2‐alkylacetic acids in the presence of N‐(3‐dimethyl‐aminopropyl)‐N′‐ethyl carbodiimide hydrochloride‐N,N‐dimethylaminopyridine complex; ii) building of imidazole ring from 2‐alkyl‐8‐chloro‐2,3‐dihydro‐3‐methyl‐1,2,5‐benzothiadiazepin‐4(5H)‐one 1,1‐dioxide to achieve 2‐alkyl‐9‐chloro‐2,3‐dihydro‐3‐methylimidazo[1,5,4‐ef][1,2,5]benzothiadiazepin‐6(4H,7H)‐one 1,1‐dioxide; iii) preparation of thiocarbonyl derivative by treatment with Lawesson's reagent. Introduction of a 3‐methyl‐2‐butenyl chain at position 2 of above imidazobenzothiadiazepinone required protection at the 7 position with thermally removable tert‐butoxycarbonyl moiety, due to the fact that alkylation of unprotected structure proved to be regioselective for the 7 position.     

Structural determination of nerve agent markers using gas chromatography mass spectrometry after derivatization with 3‐pyridyldiazomethane

Nerve agents are a class of organophosphorous chemicals that are prohibited under the Chemical Weapons Convention. Their degradation products, phosphonic acids, are analyzed as markers of nerve agent contamination and use. Because the phosphonic acids are non‐volatile and very polar, their identification by GC‐MS requires a derivatization step prior to analysis. Standard derivatization methods for gas‐chromatography electron‐impact mass‐spectrometry analysis give very similar spectra for many alkyl phosphonic acid isomers, which complicates the identification process. We present a new reagent, 3‐pyridyldiazomethane, for preparing picolinyl ester derivatives of alkyl methylphosphonic acids facilitating the determination of their structure by enhancing predictable fragmentation of the O‐alkyl chain. This fragmentation is directed by the nitrogen nucleus of the pyridyl moiety that abstracts hydrogen from the O‐alkyl chain, inducing radical cleavage of the carbon–carbon bonds and thereby causing extensive fragmentation that can be used for detailed structure elucidation of the O‐alkyl moiety. The separability of related isomers was tested by comparing the spectra of the picolinyl esters formed from twelve hexyl methylphosphonic acid isomers. Spectral library matches and principal component analysis showed that the picolinyl esters were more effectively separated than the corresponding trimethylsilyl derivatives used in the standard operating procedures. The suggested method will improve the unambiguous structural determination process for phosphonic acids. Copyright © 2013 John Wiley & Sons, Ltd.     

Sequential C−H Borylation and N‐Demethylation of 1,1′‐Biphenylamines: Alternative Route to Polycyclic BN‐Heteroarenes

Described herein is an unprecedented access to BN‐polyaromatic compounds from 1,1′‐biphenylamines by sequential borane‐mediated C(sp²)?H borylation and intramolecular N‐demethylation. The conveniently in situ generated Piers’ borane from a borinic acid reacts with a series of N,N‐dimethyl‐1,1′‐biphenyl‐2‐amines in the presence of PhSiH₃ to afford six‐membered amine‐borane adducts bearing a C(sp²)?B bond at the C2′‐position. These species undergo an intramolecular N‐demethylation with a B(C₆F₅)₃ catalyst to provide BN‐isosteres of polyaromatics. According to computational studies, a stepwise ionic pathway is suggested. Photophysical characters of the resultant BN‐heteroarenes shown them to be distinctive from those of all‐carbon analogues.     

A Second-generation photocage for Zn2+ inspired by TPEN: characterization and insight into the uncaging quantum yields of ZinCleav chelators

Photocages have been used to elucidate the biological functions of various small molecules and Ca²⁺; however, there are very few photocages available for other metal ions. ZinCleav‐2 (1‐(4,5‐dimethoxy‐2‐nitrophenyl)‐N,N,N′,N′‐tetrakis‐pyridin‐2‐ylmethyl‐ethane‐1,2‐diamine) is a second‐generation photocage for Zn²⁺ that releases the metal ion after a light‐induced bifurcation of the chelating ligand. The structure of ZinCleav‐2 was inspired by TPEN (N,N,N′,N′‐tetrakis(2‐pyridylmethyl)ethylenediamine), which is routinely used to sequester metal ions in cells owing to its high binding affinity. Inclusion of a 2‐nitrobenzyl chromophore leads to the formation of two more weakly binding di‐(2‐picolyl)amine (DPA) fragments upon photolysis of the TPEN backbone. The desired ligand was prepared using a modified procedure used to access ZinCleav‐1 (1‐(4,5‐dimethoxy‐2‐nitrophenyl)‐N,N′‐dimethyl‐N,N′‐bis‐pyridin‐2‐ylmethyl‐ethane‐1,2‐diamine). ZinCleav‐2 has a conditional dissociation constant (K_d) of ～0.9 fM as measured by competitive titration with a quinoline‐based fluorescent sensor for Zn²⁺. The K_d of the Zn²⁺ complex of the DPA photoproducts is ～158 nM ; therefore, the ΔK_d for ZinCleav‐2 photocage is ～10⁸. A large ΔK_d is required to significantly perturb free metal ion concentrations in biological assays. The quantum yield of photolysis of apo ZinCleav‐2 and the [Zn(ZinCleav‐2)]²⁺ complex are 4.7 and 2.3 %, respectively, as determined by HPLC analysis. Proof of concept Zn²⁺ release upon photolysis of [Zn(ZinCleav‐2)]²⁺ was demonstrated using the fluorescent sensor Zinpyr‐1, and the speciation of Zn²⁺ complexes was simulated using computational methods. The influence of benzylic substituents on the quantum yield of uncaging is also analyzed with the aim of tuning the photochemical properties caged complexes for in vivo experiments.     

Mononuclear Formamidinate Complexes of Lithium and Sodium

Treatment of N,N′‐bis(aryl)formamidines (FXylH = N,N′‐bis(2,6‐dimethylphenyl)formamidine, FEtH = N,N′‐bis(2,6‐diethylphenyl)formamidine, FisoH = N,N′‐bis(2,6‐diisopropylphenyl)formamidine) with nBuLi in the presence of tmeda (= N,N,N′,N′‐tetramethylethylenediamine) led to deprotonation of the amidine affording [Li(FXyl)(tmeda)] ( 1 ), [Li(FEt)(tmeda)] ( 2 ) and [Li(Fiso)(tmeda)] ( 3 ) respectively. Similar treatment of FXylH and FisoH with [Na{N(SiMe₃)₂}] in THF and pmdeta (= N,N,N′,N″,N″‐pentamethyldiethylenetriamine) yielded [Na(FXyl)(pmdeta)] ( 4 ) and [Na(Fiso)(pmdeta)] ( 5 ). All complexes were characterised by spectroscopy (NMR and IR) and X‐ray crystallography. Due to the bulkiness of the formamidinate ligands and the multidentate nature of the supporting neutral amine ligands (tmeda and pmdeta), all compounds were mononuclear with η²‐chelating formamidinate ligands in the solid state.     

Derivatization of organophosphorus nerve agent degradation products for gas chromatography with ICPMS and TOF-MS detection

Separation and detection of seven V-type (venomous) and G-type (German) organophosphorus nerve agent degradation products by gas chromatography with inductively coupled plasma mass spectrometry (GC–ICPMS) is described. The nonvolatile alkyl phosphonic acid degradation products of interest included ethyl methylphosphonic acid (EMPA, VX acid), isopropyl methylphosphonic acid (IMPA, GB acid), ethyl hydrogen dimethylamidophosphate sodium salt (EDPA, GA acid), isobutyl hydrogen methylphosphonate (IBMPA, RVX acid), as well as pinacolyl methylphosphonic acid (PMPA), methylphosphonic acid (MPA), and cyclohexyl methylphosphonic acid (CMPA, GF acid). N-(tert-Butyldimethylsilyl)-N-methyltrifluroacetamide with 1% TBDMSCl was utilized to form the volatile TBDMS derivatives of the nerve agent degradation products for separation by GC. Exact mass confirmation of the formation of six of the TBDMS derivatives was obtained by GC–time of flight mass spectrometry (TOF-MS). The method developed here allowed for the separation and detection of all seven TBDMS derivatives as well as phosphate in less than ten minutes. Detection limits for the developed method were less than 5 pg with retention times and peak area precisions of less than 0.01 and 6%, respectively. This method was successfully applied to river water and soil matrices. To date this is the first work describing the analysis of chemical warfare agent (CWA) degradation products by GC–ICPMS. Figure Illustrated here are six parent organophosphorus nerve agents corresponding to the degradation products analyzed by gas chromatography with ICPMS and ToF-MS detection. The authors would like to thank Daisy-Malloy Hamburg and Kevin M. Kubachka for creating this figure     

Monomers for adhesive polymers. XV. Synthesis,photopolymerization, and adhesive properties of polymerizable β‐ketophosphonic acids

The novel polymerizable β‐ketophosphonic acids 4 , 8 , 10 , and 16 as well as the 9‐(methacryloyloxy)‐nonylphosphonic acid 20 were synthesized in four to eight steps. They were characterized by ¹H NMR, ¹³C NMR, and ³¹P NMR spectroscopy and by high‐resolution mass spectra. The free‐radical polymerization of 4 , 8 , 10 , and 16 was carried out in a water/ethanol solution, using 2,2′‐azo(2‐methylpropionamidine)dihydrochloride as initiator. To evaluate the reactivity of the acidic monomers 4 , 8 , 10 , 16 , and 20 , their photopolymerization behavior was investigated by photodifferential scanning calorimeter. Copolymerizations with 2‐hydroxyethyl methacrylate, glycol dimethacrylate, and N,N′‐diethyl‐1,3‐bis‐(acrylamido)propane were studied. The homopolymerization of the corresponding β‐ketophosphonates and their copolymerization with hydroxyethyl methacrylate were also carried out. Self‐etch adhesives based on the β‐ketophosphonic acids 4 , 8 , 10 , and 16 were able to provide high shear bond strengths (SBSs) of dimethacrylate‐based composite to dentin and enamel. The β‐ketophosphonic acid 8 was also shown to exhibit significantly better adhesive properties than the corresponding phosphonic acid 20 . Indeed, the presence of the carbonyl moiety in the β‐position of the phosphonic acid group led to a strong improvement of the composite SBS to dentin and enamel. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3550–3563