Rigid Dicarboxylic Acids Research Articles

Synthesis, characterization and hydrolytic degradation of novel biodegradable poly(ester amide)s derived from Isosorbide and α-amino acids

A series of poly(ester amide)s (PEAs) derived from the nontoxic building blocks, isosorbide, α-amino acids (L-phenylalanine, L-alanine, L-valine and glycine) and dicarboxylic acids was synthesized by interfiactial polymerization using a two-step method. The majority of PEAs were amorphous except for some glycine containing polymers. The PEAs showed good thermal stabilities and had Tg temperatures from 115.9 to 182.6 °C. The hydrolytic degradation behavior of the PEAs was followed by weight loss in both alkaline solution (pH 9) and under stimulated physiological conditions (pH 7.4) in phosphate buffer saline solution at 37 °C. The polymers with hydrophobic pendent or rigid dicarboxylic acid groups prevent degrading media from penetration into the polymer bulk leading to slow degradation rate. The monomers synthesized were characterized by FTIR, 1H and 13C NMR spectroscopy, the PEAs structures were confirmed by FTIR, 1H and 13C NMR spectroscopy and their thermal properties were studied by TGA and DSC.

Electron Density Distribution of Urea in Co-crystals with Rigid and Flexible Dicarboxylic Acids

This is the first study on electron density distribution of urea and dicarboxylic acids co-crystals. The accurate electron density of two co-crystals of urea with oxalic acid and l-malic acid molecules is discussed, on the basis of high-resolution X-ray diffraction data collected at 80(2) K, and compared with density functional theory calculations in a crystal structure as well as in the gas phase. Rigid dicarboxylic acid favors two-dimensional planar hydrogen bond networks, whereas flexible acid promotes layers with helical arrangements of those molecules. The nature of chemical bonding is investigated using topological analysis based on quantum atoms in molecules theory, Hirshfeld analysis, noncovalent interactions approach, distributed atomic polarizabilities and electrostatic potential. In a co-crystal of oxalic acid and urea, uncommon carbonyl···carbonyl interaction is observed, representing an antiparallel motif between oxalic and urea molecules, which was so far identified only between the same molecules.

Synthesis and Structure of novel Luminescent lanthanide organic frameworks.

Lanthanide-Organic frameworks (LnOFs) are currently attracting increasing attention due to their excellent luminescence properties, in which both Ln3+ and organic linkers can be used to give rise to luminescence materials with increased brightness and emission quantum yield [1,2]. Lithium doped MOFs are of particular interest due to the recent studies showing enhanced H2 uptake, as well as promising candidates for replacing the conventional electrode in Li-ion batteries [3,4]. Herein, novel Lithium-lanthanide frameworks based on a rigid dicarboxylic acid, formulated as [LiLn(BDC)2(H2O)·2(H2O)] (Ln = Y, Dy, Ho, Er, Yb, Y1-xEux, Y1-xTbx and H2BDC = Terephthalic acid), have been obtained as single phases under hydrothermal conditions. The crystal structures were solved by single-crystal X-ray diffraction and the bulk characterized by powder X-ray diffraction (PXRD), thermal analyses (TG-MS and DSC), vibrational spectroscopy (FTIR), scanning/transmission electron microscopy (SEM-EDX, TEM, SAED, STEM-EDX), and powder X-ray thermodiffractometry (HT-XRD). All compounds are isostructural (monoclinic P21/c, a = 11.6365(7) Å, b =16.0920(2) Å, c = 13.2243(8) Å and β = 132.23(1)° for Ln = Y [5]) and possess a 3D framework with 1D trigonal channels running along the [101] direction contain water molecules. The structure is built up of unusual four-membered rings formed by edge- and vertex-shared {LnO8} and {LiO4} polyhedra. The four-membered rings are isolated and connected to each other via carboxylate groups. Topologically, the 3D frameworks belongs to a new 2-nodal 3,10-c net with point symbol of {4.5^2}2{4^14.5^10.6^18.7.8^2}. HT-XRD reveals that the compounds undergo phase transformation upon dehydration process which is a reversible process involving a spontaneous rehydration characterized by fast kinetic. The luminescence properties of selected compounds are also studied.

Four MOFs with 2,2′-dimethoxy-4,4′-biphenyldicarboxylic acid: syntheses, structures, topologies and properties

Four novel metal–organic frameworks, [MnL(DMF)]n (1), [NiL(H2O)2(DMF)]n (2), [Cu2L2(H2O)2]·6H2O·2DMF (3), and Na2(Me2NH2)4[Cd7L10]·9H2O·17Me2NH·2DMF (4), were successfully synthesized in solvothermal conditions using 2,2′-dimethoxy-4,4′-biphenyldicarboxylic acid (H2L) as the ligand. The X-ray crystallography analysis reveals that MOF 1 exhibits a 3D framework with sra topology, while MOF 2 shows a 2D network with sql topology though they possess a similar secondary building unit (SBU) [MO6] (M = Mn for 1 and Ni for 2). MOF 3 reveals an unprecedented 4-fold interpenetrated 3D framework with lvt topology constructed from only planar 4-connected nodes ([Cu2(CO2)4] SBUs) with the rigid dicarboxylic acids. MOF 4 features an unique acentric 3D/3D hetero-interpenetrated framework built from two different nodes (4- and 8-connected), different chemical compositions [Cd(CO2)4 and Cd3(CO2)8], and different topology of networks (66 and 424·64) and contains an inorganic 1D chain consisting of a Na+ and three Cd2+ ions. The solid state 113Cd NMR spectrum indicates that 4 has three 6-, 7-, and 8-coordinated Cd2+ ions with chemical shifts at δ −25.3, −41.2 and −83 ppm, respectively. MOF 3 has two kinds of 1D channels with diameters of 11 A and 7 A and exhibits a selective gas adsorption for CO2–N2 and CH4–N2. MOF 4 shows a selective adsorption for cationic dyes and a nonlinear SHG activity (ca. 0.8 times that of urea).

Hydrogen bonded binary molecular adducts derived from exobidentate N-donor ligand with dicarboxylic acids: Acid⋯imidazole hydrogen-bonding interactions in neutral and ionic heterosynthons

Four new binary molecular compounds between a flexible exobidentate N-heterocycle and a series of dicarboxylic acids have been synthesized. The N-donor 1,4-bis(imidazol-1-ylmethyl)benzene (bix) was reacted with flexible and rigid dicarboxylic acids viz., cyclohexane-1,4-dicarboxylic acid (H 2chdc), naphthalene-1,4-dicarboxylic acid (H 2npdc) and 1H-pyrazole-3,5-dicarboxylic acid (H 2pzdc), generating four binary molecular complexes. X-ray crystallographic investigation of the molecular adducts revealed the primary intermolecular interactions carboxylic acid⋯amine (via O–H⋯N) as well as carboxylate⋯protonated amine (via N–H +⋯O −) within the binary compounds, generating layered and two-dimensional sheet type H-bonded networks involving secondary weak interactions (C–H⋯O) including the solvent of crystallization. Depending on the differences in p K a values of the selected base/acid (Δp K a), diverse H-bonded supramolecular assemblies could be premeditated. This study demonstrates the H-bonding interactions between imidazole/imidazolium cation and carboxylic acid/carboxylate anion in providing sufficient driving force for the directed assembly of binary molecular complexes. In the two-component solid form of hetero synthons involving bix and dicarboxylic acid, only H 2chdc exist as cocrystal with bix, while all the other three compounds crystallized exclusively as salt, in agreement with the Δp K a values predicted for the formation of salts/cocrystals from the base and acid used in the synthesis of supramolecular solids.

A Microporous Metal−Organic Framework Based on [2 + 2] Parallel and Inclined Interpenetrated 2D Sheets Interconnected by an Auxiliary Linker

A microporous metal−organic framework (MOF), [Zn2L2(dabco)], was prepared using a long and rigid dicarboxylic acid, 1,4-bis(3-carboxylphenylethynyl)benzene (H2L), with some rotational flexibility, and an auxiliary bridging diamine linker, 1,4-diazabicyclo[2.2.2]octane (dabco). The MOF, based on a Zn paddle-wheel secondary building unit, has [2 + 2] parallel and inclined interpenetrating 2D sheets interconnected by dabco to form a 3D network with 1D helical channels.

Fine-Tuning Ligand−Receptor Design for Selective Molecular Recognition of Dicarboxylic Acids

The host-guest interaction between the hexaaza macrocyclic ligand 3,7,11,18,22,26-hexaazatricyclo[26.2.2.2]tetratriaconta-1(31),13(34),14,16(33),28(32),29-hexaene (P3) and three rigid dicarboxylic acids (isophthalic acid, H2is; phthtalic acid, H2ph; and terephthalic acid, H2te) has been investigated using potentiometric equilibrium methods and NMR spectroscopy including the measurement of intermolecular nuclear Overhauser effects (NOEs) and self-diffusion coefficients (D). Ternary complexes are formed in aqueous solution as a result of hydrogen bond formation and Coulombic interactions between the host and the guest. In the [(H6P3)(is)]4+ complex, those bonding interactions reach a maximum yielding a log K6R of 4.74. Competitive distribution diagrams and total species distribution diagrams are used to illustrate the main features of these systems. In particular, a selectivity of over 89% at p[H] = 5.0 is obtained for the complexation of the is versus the te substrates. The recognition capacity of P3 over dicarboxylic acids (da) is compared to the related hexaaza macrocycle Me2P3 (7,22-dimethyl-3,7,11,18,22,26-hexaazatricyclo[26.2.2.2]tetratriaconta-1(30),13,15,28,31,33-hexaene) that binds da with a lesser strength, and it is not selective. Theoretical calculations performed at molecular dynamics level have also been carried out and point out that the origin of selectivity is mainly due to the capacity of the P3 ligand receptor to adapt to the geometry of the dicarboxylic acid to form relatively strong hydrogen bonds.

Synthesis and Properties of Novel Aromatic Poly(ester amide)s Bearing Naphthalene-2,7-diyl Units

Two new naphthalene ring-containing diamino-diesters, 2,7-bis(4-aminobenzoyloxy)naphthalene (p-2) and 2,7-bis(3-aminobenzoyloxy)naphthalene (m-2), were synthesized from the condensation of 2,7-dihydroxynaphthalene with 4-nitrobenzoyl chloride and 3-nitrobenzoyl chloride, respectively, followed by catalytic hydrogenation. Two series of naphthalene-containing poly(ester amide)s with inherent viscosities of 0.49–0.97 and 0.36–0.73 dL g-1 were prepared by the phosphorylation polyamidation of p-2 and m-2, respectively, with various aromatic dicarboxylic acids. Most of the poly(ester amide)s had excellent solubilities in polar aprotic solvents such as N-methyl-2-pyrrolidone and N,N-dimethylacetamide, especially for the m-series polymers. Some of the poly(ester amide)s could be cast into transparent, flexible, and tough films from DMAc solutions. The poly(ester amide)s derived from rigid dicarboxylic acids such as terephthalic acid, 4,4’-biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid and 4,4’-sulfonyldibenzoic acid were semicrystalline and showed less solubility. Except for three examples, most of the poly(ester amide)s displayed discernible glass transitions between 187 and 237 °C in the DSC traces. These poly(ester amide)s showed insignificant decomposition below 400 °C in nitrogen or air. The investigation of the thermal decomposition of the poly(ester amide)s using infrared spectroscopy and pyrolysis-gas chromatography/mass spectrometry (pyrolysis-GC/MS) indicated that the primary breakage of the ester linkages started at around 400 °C, which initiated the polymer chain scission.

Platinum(II) phosphine complexes of dicarboxylates and ammonia: crystal structures of [{Pt(PPh3)2}2{µ -1,3-(O2C)2C6H4}2], [{Pt(PPh3)2(NH3)}2{µ-1,4-(O2C)2C6H4}][PF6]2and cis-[Pt(PPh3)2(NH3)2][NO3]2

The reaction of [Pt(PPh 3 ) 2 (CO 3 )] with a rigid dicarboxylic acid H 2 L gave rise to dimeric compounds [{Pt(PPh 3 ) 2 } 2 (µ-L) 2 ] 1 [H 2 L = C 6 H 4 (CO 2 H) 2 -1,4 (terephthalic acid) a, C 6 H 4 (CO 2 H) 2 -1,3 (isophthalic acid) b, trans,trans-HO 2 CCHCHCH CHCO 2 H (muconic acid) c or 4,4′-HO 2 CC 6 H 4 C 6 H 4 CO 2 H (biphenyldicarboxylic acid) d], which have been characterised spectroscopically and, in the case of 1b, crystallographically. When the reaction was carried out in the presence of NH 4 PF 6 the NH 4 + competed with the carboxylic acid and the major product from the reaction was [{Pt(PPh 3 ) 2 (NH 3 )} 2 (µ-L)][PF 6 ] 2 2, which has been characterised crystallographically for L = terephthalate. This suggests that NH 4 + is acidic enough to react with [Pt(PPh 3 ) 2 (CO 3 )], which has been confirmed by the synthesis of cis-[PtL 2 (NH 3 ) 2 ]X 2 [L = PPh 3 , X = PF 6 3a or NO 3 3b; L = PEt 3 , X = PF 6 4a or NO 3 4b; L 2 = Ph 2 PCH 2 CH 2 PPh 2 (dppe), X = PF 6 5a] from [PtL 2 (CO 3 )]. The complex cis-[Pt(PPh 3 ) 2 ( 15 NH 3 ) 2 ][NO 3 ] 2 was synthesized from 15 NH 4 NO 3 and characterised by a combination of 31 P-{ 1 H}, 15 N-{ 1 H}, 195 Pt and 1 H NMR spectroscopy. The crystal structure of cis-[Pt(PPh 3 ) 2 (NH 3 ) 2 ][NO 3 ] 2 3b has been determined and shows strong hydrogen bonding between the co-ordinated ammonia and the nitrate counter ions. The compound PhC 2 CO 2 H also reacted with [PtL 2 (CO 3 )], though the products were not the expected bifunctional carboxylates cis-[PtL 2 (O 2 CC 2 Ph) 2 ] but the bis(phenylalkynyl) compounds cis-[PtL 2 (C 2 Ph) 2 ] (L = PPh 3 6, L 2 = dppe 7).

Synthesis and properties of aromatic polyamides derived from 1,6‐bis(4‐aminophenoxy)naphthalene and aromatic dicarboxylic acids

AbstractA new bis(phenoxy)naphthalene‐containing diamine, 1,6‐bis(4‐aminophenoxy)naphthalene, was synthesized in two steps from the condensation of 1,6‐dihydroxynaphthalene with p‐chloronitrobenzene in the presence of potassium carbonate, giving 1,6‐bis(4‐nitrophenoxv)naphthalene, followed by hydrazine hydrate/Pd—C reduction. A series of polyamides were synthesized by the direct polycondensation of the diamine with various aromatic dicarboxylic acids in the N‐methyl‐2‐pyrrolidone (NMP) solution containing dissolved metal salts such as CaCl2 or LiBr using triphenyl phosphite and pyridine as condensing agents. The polymers were obtained in quantitative yield with inherent viscosities of 0.78–3.72 dL/g. Most of the polymers were soluble in aprotic solvents such as N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide (DMF), NMP, and they could be solution‐cast into transparent, flexible and tough films. The casting films had tensile strength of 102–175 MPa, elongation at break of 8–42%, and tensile modulus of 2.4–3.8 GPa. The polymers derived from rigid dicarboxylic acids such as terephthalic acid and 4,4′‐biphenyldicarboxylic acid exhibited some crystalline characteristics. The glass transition temperatures of the polyamides were in the range of 238–337°C, and their 10% weight loss temperatures were above 487°C in nitrogen and above 438°C in air. © 1995 John Wiley & Sons, Inc.

Cross-linking hemoglobin by design: lessons from using molecular clamps.

The development of a red cell substitute by chemical modification of hemoglobin has been approached as a systematic, iterative process. Acyl phosphate methyl esters were designed as anionic electrophiles to permit selective acylation of amino groups in the cationic site of hemoglobin which binds polyanions. Kinetic studies with systematically substituted acyl phosphates and amines show that the reaction is controlled by a reversible addition step followed by an irreversible elimination step. Acyl phosphate methyl esters which are derivatives of rigid dicarboxylic acids introduce cross-links in human hemoglobin between amino groups in the beta subunits (epsilon-NH2-Lys-82, alpha-NH2-Val-1) and permit correlation of oxygen binding properties with cross-link structure. The data suggest that the cross-link maintains cooperativity while reducing overall oxygen affinity by lowering the affinity of the R form for oxygen rather than by perturbing the R,T equilibrium of native hemoglobin. Materials produced from deoxyhemoglobin with a cross-link between positions 1 and 82 of the two beta units have appropriate oxygen affinity for red cell substitutes. The use of a trifunctional cross-linker, trimesyl tris(methyl phosphate) selectively produces hemoglobin with the desired 1-82 connection in good yield. The reagent is readily prepared and the properties of this chemically modified hemoglobin are suitable for trial as a red cell substitute, closely resembling those of optimized materials produced by recombinant technology. Further work is producing new chemicals and providing structural information.

Synthesis and properties of novel aromatic polyamides derived from 1,5‐bis(4‐aminophenoxy)naphthalene and aromatic dicarboxylic acids

AbstractA new bis(phenoxy)naphthalene‐containing diamine, 1,5‐bis(4‐aminophenoxy)naphthalene, was synthesized in two steps from the condensation of 1,5‐dihydroxy‐naphthalene with p‐chloronitrobenzene in the presence of potassium carbonate, giving 1,5‐bis(4‐nitrophenoxy)naphthalene, followed by hydrazine hydrate/PdC reduction. A series of polyamides and copolyamides were synthesized by the direct polycondensation of the diamine with various aromatic dicarboxylic acids or with mixed dicarboxylic acids in N‐methyl‐2‐pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. The polymers having inherent viscosity of 0.81–1.25 dL/g were obtained in quantitative yield. Most of the polymers were generally soluble in aprotic solvent such as N,N‐dimethylacetamide, N‐methyl‐2‐pyrrolidone, etc. The polymers derived from rigid dicarboxylic acids such as terephthalic acid, naphthalene dicarboxylic acid, and 4,4′‐biphenyldicarboxylic acid exhibited crystalline patterns. Glass transition temperatures of polymers were in the range of 230–360°C, and 10% weight loss temperatures in nitrogen and air were above 492 and 470°C, respectively. © 1993 John Wiley & Sons, Inc.

Synthesis and aggregation properties of a new family of amphiphiles with an unusual headgroup topology

A new family of amphiphiles, derived from a rigid dicarboxylic acid headgroup unit of unusual topology, has been synthesized. The aggregation of these molecules in aqueous solution has been examined by 1 H NMR and dye solubilization methods. Two modes of aggregation appear to be operative within this group of amphiphiles, one determined by the headgroup and the other determined by the flexible tail. The former mode is dominant when the tail is short or nonexistent, and the latter is dominant when the tail contains six or more nonpolar atoms. The latter mode appears to be a typical micellization process, but the former is less cooperative