Preparation and characterization of hexamethylenetetramine‐functionalized magnetic nanoparticles and their application as novel catalyst for the synthesis of pyranopyrazole derivatives

A new magnetic catalyst was prepared through the reaction of silanol groups, on the surface of silica‐coated Fe₃O₄ magnetic nanoparticles, with (3‐chloropropyl)triethoxysilane followed by hexamethylenetetramine and chlorosulfonic acid. The obtained magnetic catalyst was characterized using thermogravimetric analysis, vibrating sample magnetometry, scanning electron microscopy and energy‐dispersive X‐ray analysis. Its catalytic activity was investigated in the synthesis of pyranopyrazole compounds, and the results were excellent regarding high yield of the products and short reaction time.     

Efficient synthesis of multiply substituted furans using BF@Propyl/dopamine/Pd as a green catalyst

One of the commonly used methods to synthesize furans is the three-component reaction among aromatic aldehyde, arylamine, and acetylenedicarboxylate. The main advantages of this work are easy reaction work-up, short reaction time, high yield and easy recyclability, reusability of the catalyst. And also basalt fiber applications are surely innovative in many industrial and economic fields, because of its good mechanical, chemical and thermal performances.     

Reducing the computational cost of NMR crystallography of organic powders at natural isotopic abundance with the help of 13C-13C dipolar couplings

Structure determination of functional organic compounds remains a formidable challenge when the sample exists as a powder. Nuclear magnetic resonance crystallography approaches based on the comparison of experimental and Density Functional Theory (DFT)-computed ¹H chemical shifts have already demonstrated great potential for structure determination of organic powders, but limitations still persist. In this study, we discuss the possibility of using ¹³C-¹³C dipolar couplings quantified on powdered theophylline at natural isotopic abundance with the help of dynamic nuclear polarization, to realize a DFT-free, rapid screening of a pool of structures predicted by ab initio random structure search. We show that although ¹³C-¹³C dipolar couplings can identify structures possessing long range structural motifs and unit cell parameters close to those of the true structure, it must be complemented with other data to recover information about the presence and the chemical nature of the supramolecular interactions.     

Decorations of graphene oxide with cisplatin toward investigation of fluorescence quencher on regulatory sequence of BRCA1 and BRCA2

Journal of the Iranian Chemical Society - Herein, we investigated the interaction of cisplatin loaded on GO (GO@CDDP) with two regulatory sequences, BRCA1 and BRCA2, synthesized from ssDNA based on...     

Integrating Rigidity Analysis into the Exploration of Protein Conformational Pathways Using RRT* and MC

To understand how proteins function on a cellular level, it is of paramount importance to understand their structures and dynamics, including the conformational changes they undergo to carry out their function. For the aforementioned reasons, the study of large conformational changes in proteins has been an interest to researchers for years. However, since some proteins experience rapid and transient conformational changes, it is hard to experimentally capture the intermediate structures. Additionally, computational brute force methods are computationally intractable, which makes it impossible to find these pathways which require a search in a high-dimensional, complex space. In our previous work, we implemented a hybrid algorithm that combines Monte-Carlo (MC) sampling and RRT*, a version of the Rapidly Exploring Random Trees (RRT) robotics-based method, to make the conformational exploration more accurate and efficient, and produce smooth conformational pathways. In this work, we integrated the rigidity analysis of proteins into our algorithm to guide the search to explore flexible regions. We demonstrate that rigidity analysis dramatically reduces the run time and accelerates convergence.     

Fe3O4@SiO2@propyl‐ANDSA: A new catalyst for the synthesis of tetrazoloquinazolines

In this paper, a mild and green protocol has been developed for the synthesis of quinazoline derivatives. The catalytic activity of 7‐aminonaphthalene‐1,3‐disulfonic acid‐functionalized magnetic Fe₃O₄ nanoparticles (Fe₃O₄@SiO₂@Propyl–ANDSA) was investigated in the one‐pot synthesis of new derivatives of tetrahydrotetrazolo[1,5‐a]quinazolines and tetrahydrobenzo[h]tetrazolo[5,1‐b]quinazolines from the reaction of aldehydes, 5‐aminotetrazole, and dimedone or 6‐methoxy‐3,4‐dihyronaphtalen‐1(2H)‐one at 100 °C in H₂O/EtOH as the solvent. The catalyst was characterized before and after the organic reaction. Fe₃O₄@SiO₂@Propyl–ANDSA showed remarkable advantages in comparison with previous methods. Advantages of the method presented here include easy purification, reusability of the catalyst, green and mild procedure, and synthesis of new derivatives in high yields within short reaction time.     

N,N ′-Diiodo-N,N′-1,2-ethanediylbis(p-toluenesulfonamide) as an Efficient Catalyst for Acetylation of Alcohols,Phenols, Amines,and Thiols Under Solvent-Free Conditions

N,N′-Diiodo-N,N′-1,2-ethanediylbis(p-toluenesulfonamide) (NIBTS) is a highly efficient catalyst for the acetylation of alcohols, phenols, amines, and thiols under solvent-free conditions. Primary, secondary, tertiary alcohols; phenols; amines; and thiols can be easily acetylated in good to excellent yields at 80 °C.     

FACILE AND EFFICIENT METHOD FOR DEPROTECTION OF 1,3-OXATHIOLANES WITH N,N′-DIBROMO-N,N′-1,2-ETHANEDIYLBIS(p-TOLUENESULPHONAMIDE)

Aliphatic and aromatic 1,3-oxathiolanes[3pc] are readily oxidized to aldehydes and ketones in good yields under mild conditions by N,N′-dibromo-N,N′-1,2-ethanediylbis(p-toluenesulphonamide) [BNBTS].