Optically transparent,organosoluble poly(ether-amide)s bearing triptycene unit; synthesis and characterization

Abstract

Aromatic polyamides are famous high performance polymeric materials for their excellent thermal, mechanical, electrical properties, which now a days became a dominant platform for modern polymer chemistry area. Triptycene unit like structures in polymer directly affects the physiochemical properties of polymer, thus polyamides especially with triptycene unit in their backbone with aryl ether linkage imparts combination of properties such as better solubility, melts processing characteristics, and better thermal stability in contrast with those of polymers without an aryl-ether linkageNew triptycene-containing bis(ether amine), 1,4-bis(4-aminophenoxy), 2, 3-benzotriptycene (4a) was synthesized from nucleophilic displacement reactions of P-fluoronitrobenzene with 1,4-dihydroxytriptycene, followed by reduction, and elucidated by FTIR, ^1?H, ^13?C NMR spectroscopy and HRMS. A series of new polyamides containing pendant triptycene group and flexibilizing ether linkages was synthesized by polycondensation of diamine with commercially available aromatic diacischlorides viz., terephthalylchloride (TPC), isophthalylchloride (IPC) and varying molar mixture of TPC and IPC accordingly. Synthesized Poly(ether-amide)s were found soluble in common organic solvents such as chloroform, dichloromethane, tetrahydrofuran, DMF, DMAc, DMSO also could be cast into excellent transperent thin films. Inherent viscosities of polyamides were in the range 0.44–0.57 dL/g. Polyamides exhibited initial decomposition temperature (T_i), glass transition temperatures (T_g) and temperature at 10% wt loss (t₁₀), which was determined by TGA were noted in the range 212?°C–305?°C, 295?°C –309?°C and 587?°C–631?°C respectively with 24%–54% char yeild at 900?°C under nitrogen atmosphere, indicating its better thermal stability and moderate glass transition temperature.     

A Fast and Large-Scale Synthesis of 3-Formyl-2-mercaptoquinolines

A convenient, efficient, and inexpensive procedure for the synthesis of 3-formyl-2-mercaptoquinolines 2a–l has been developed by a simple one-pot reaction of 3-formyl-2-chloroquinolines 1a–l with sodium sulfide and hydrochloric acid in ethanol. The structures of all the synthesized compounds were elucidated on the basis of elemental analyses and IR, ¹ H NMR, and mass spectral data.     

Covalently Linked Plasticizers: Triazole Analogues of Phthalate Plasticizers Prepared by Mild Copper‐Free “Click” Reactions with Azide‐Functionalized PVC

Copper‐free azide‐alkyne click chemistry is utilized to covalently modify polyvinyl chloride (PVC). Phthalate plasticizer mimics di(2‐ethylhexyl)‐1H‐triazole‐4,5 dicarboxylate (DEHT), di(n‐butyl)‐1H‐1,2,3‐triazole‐4,5‐dicarboxylate (DBT), and dimethyl‐1H‐triazole‐4,5‐dicarboxylate (DMT) are covalently attached to PVC. DEHT, DBT, and DMT have similar chemical structures to traditional plasticizers di(2‐ethylhexyl) phthalate (DEHP), di(n‐butyl) phthalate (DBP), and dimethyl phthalate (DMP), but pose no danger of leaching from the polymer matrix and forming small endocrine disrupting chemicals. The synthesis of these covalent plasticizers is expected to be scalable, providing a viable alternative to the use of phthalates, thus mitigating dangers to human health and the environment.

     

Single vial formulation for theranostic radiopharmaceutical preparation

The present work was aimed at development of pharmaceutical grade single vial kit like formulation of somatostatin analogue, DOTA–Tyr³–Thr⁸-Octreotide (DOTATATE) suitable for radiolabeling with both diagnostic (⁶⁸Ga) and therapeutic (¹⁷⁷Lu) radioisotope. Single vial kit like formulation of DOTATATE was prepared. Radiolabeling methods with ⁶⁸Ga and ¹⁷⁷Lu were standardized. The pharmaceutical purity and stability of formulation was studied over a period of 6 months. Pharmacokinetics of radiolabeled preparations was studied in Swiss mice. DOTATATE formulation with 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer was successfully prepared. Both ⁶⁸Ga–DOTATATE and ¹⁷⁷Lu–DOTATATE complexes were formed with >95 % radiochemical purity. Biodistribution studies of ⁶⁸Ga–DOTATATE and ¹⁷⁷Lu–DOTATATE complexes in Swiss mice revealed fast clearance of activity via renal route. Single vial kit like formulation suitable for easy preparation of ⁶⁸Ga–DOTATATE and ¹⁷⁷Lu–DOTATATE at hospital radiopharmacy was successfully demonstrated.     

Synthesis and evaluation of a phenylbenzothiazole-based 99mTc(CO)3-radiotracer for possible application in imaging of β-amyloid plaques in Alzheimer’s disease

The 2-phenyl benzothiazole pharmacophore is known to have high affinity for amyloid beta (Aβ) and is therefore derivatized, to [N-(4′-benzothiazol-pyridin-2-yl-methyl-amino)-acetic acid (BTPAA)] for radiolabeling with [^99mTc(CO)₃(H₂O)₃]⁺ precursor. The radiotracer, ^99mTc(CO)₃–BTPAA is evaluated in vitro and in vivo to determine its binding with the Aβ and ability to cross the blood brain barrier. The radiotracer prepared in >95 % radiochemical yield, showed ~25 % inhibition in presence of thioflavin-T, indicating its specificity towards aggregated Aβ protein. The radiotracer also showed brain uptake of 0.25 ± 0.04 % injected dose/g at 2 min post injection, indicating its ability to cross the blood brain barrier.     

Dynamic solvation in phosphonium ionic liquids: comparison of bulk and micellar systems and considerations for the construction of the solvation correlation function, C(t)

Dynamic solvation of the dye coumarin 153 is studied in a phosphonium ionic liquid: hexadecyltributylphosphonium bromide, [(C4)3C16P+][Br-]. It forms micelles in water, and the bulk also exists as a liquid under our experimental conditions. This system permits a comparison with an imidazolium ionic liquid studied earlier, which also formed micelles in water (J. Phys. Chem. A 2006, 110, 10725-10730). We conclude that our analysis of the comparable situation in a phosphonium liquid is not as definitive as we had proposed earlier, i.e., that the majority of the early-time solvation arises from the organic cation. Part of the difficulty in performing this analysis is most likely due to the amount of water that is associated with the micelle. In the course of this work, we have focused on the calculation of the solvation correlation function, C(t), and investigated how it depends upon the methods with which the "zero-time" spectrum is constructed.     

A new approximate method for the stochastic simulation of chemical systems: the representative reaction approach

We have developed two new approximate methods for stochastically simulating chemical systems. The methods are based on the idea of representing all the reactions in the chemical system by a single reaction, i.e., by the “representative reaction approach” (RRA). Discussed in the article are the concepts underlying the new methods along with flowchart with all the steps required for their implementation. It is shown that the two RRA methods {with the reaction as the representative reaction (RR)} perform creditably with regard to accuracy and computational efficiency, in comparison to the exact stochastic simulation algorithm (SSA) developed by Gillespie and are able to successfully reproduce at least the first two moments of the probability distribution of each species in the systems studied. As such, the RRA methods represent a promising new approach for stochastically simulating chemical systems. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2012     

Synthesis and spectroscopic studies on copper(II) binuclear complexes of 1-phenylamidino-O-alkylurea (alkyl = n-propyl, n- and iso-butyl) with 1,3-diaminopropane or ethylenediamine

Copper(II) binuclear complexes [Cu(II)(1-phenylamidino-O-n-propylurea)tn]2 (H2O)2(Cl2)2 (1), [Cu(II)(1-phenylamidino-O-n-butylurea)tn]2(H2O)2(Cl2)2(2), [Cu(II)(1-phenylamidino-O-i-butylurea)tn]2(H2O)2(Cl2)2(3), and [Cu(II)(1-phenyamidino-O-i-butylurea)en]2(H2O)2(Cl2)2 (4) have been reported. The binuclear complexes 3 and 4 crystallize in a monoclinic structure with unit cell dimensions a = 15.252(17) A, b = 14.682(10) A, c = 13.606(13) A, and beta = 111.2(1) degrees and a = 15.278(35) A, b = 14.665(21) A, c = 13.603(27) A, and beta = 111.1(1) degrees , respectively. The EPR spectra of all the solid complexes at room temperature consisted of fine-structure transitions (DeltaM(s) = 1) with zero-field splitting (ZFS) of 0.0500 cm(-1) and a half-field signal (DeltaM(s) = 2) at ca. 1600 G, suggesting the formation of binuclear complexes (S = 1). From the observed ZFS, we estimated the average Cu-Cu distance. From the temperature dependence of the EPR signal intensity, we evaluated the isotropic exchange interaction constant J. It appears that the exchange interaction between the two interacting spins of the binuclear complexes is ferromagnetic in nature. The formation of ferromagnetically coupled copper binuclear complexes was further confirmed from the high magnetic-moment values at room temperature. When the EPR spectra were recorded in the temperature range 300-400 K, it was observed that the triplet-state EPR signal completely and irreversibly disappeared at ca. 380 K with the appearance of a new signal attributable to the mononuclear complex (S = 1/2). Thermal studies of these complexes in this temperature range suggested the loss of two water molecules, which might be responsible for binding two mononuclear species. EPR, IR, and thermal studies indicate a long-range ferromagnetic exchange mediated through hydrogen bonding between copper(II) ions (S = 1/2).     

Mucin at solution/air and solid/solution interfaces

In this paper the surface activity of protein mucin at solution/air interface has been studied. The experiments of the adsorbed protein at solution/air interface have been carried out with a range of protein concentrations at a defined pH. The adsorption of the protein to solid surfaces and the degree of hydrophobicity at solid/solution interface of mucin have been evaluated at different pH and in the presence of Hofmeister electrolyte. The results from these studies have been further substantiated by surface potential measurements of mucin covered surface on stainless steel. Quartz crystal microbalance (QCM) has been used to follow the protein adsorption kinetics from solution to solid surface. The results from these measurements show that the adsorption behavior has a remarkable dependence on the degree of maximum coverage and is almost independent of the ionic strength. Other characteristic features such as maximum adsorption values at the protein isoelectric point (IEP4.7) and low-affinity isotherms that showed surface saturation even under unfavorable electrostatic conditions have been observed. The amount of mucin adsorbed in the presence of electrolytes has been estimated using electron spectroscopy for chemical analysis (ESCA). The study clearly shows that there exists an inverse relationship between the hydrophobicity and surface tension of the protein and also on the hydrated radius of Hofmeister electrolyte used.     

Synthetic application of in situ generation of N-acyliminium ions from α-amido p-tolylsulfones for the synthesis of α-amino nitriles

In the presence of catalytic amount of bismuth bromide (5 mol %) the α-amido p-tolylsulfones are converted into N-acyliminium ions, which undergo the nucleophilic addition of trimethylsilyl cyanide (TMSCN) to provide the N-protected α-amino nitriles in very good yield. A variety of α-amido p-tolylsulfones were prepared from aromatic as well as aliphatic aldehydes for the synthesis of α-amino nitriles.