RESUMEN
Nitroaromatics are tremendously valuable organic compounds with a long history of being used as pharmaceuticals, agrochemicals, and explosives as well as vital intermediates to a wide variety of chemicals. Consequently, the exploration of aromatic nitration has become an important endeavor in both academia and industry. Herein, we report the identification of a powerful nitrating reagent, 5-methyl-1,3-dinitro-1H-pyrazole, from the N-nitro-type reagent library constructed using a practical N-H nitration method. This nitrating reagent behaves as a controllable source of the nitronium ion, enabling mild and scalable nitration of a broad range of (hetero)arenes with good functional group tolerance. Of note, our nitration method could be controlled by manipulating the reaction conditions to furnish mononitrated or dinitrated product selectively. The value of this method in medicinal chemistry has been well established by its efficient late-stage C-H nitration of complex biorelevant molecules. Density functional theory (DFT) calculations and preliminary mechanistic studies reveal that the powerfulness and versatility of this nitrating reagent are due to the synergistic "nitro effect" and "methyl effect".
RESUMEN
Two models for predicting the density of organic cocrystals composed of energetic organic cocrystals and general organic cocrystals containing nitro groups were obtained. Sixty organic cocrystals in which the ratio of component molecules is 1 : 1 were studied as the dataset. Model-I was based on the artificial neural network (ANN) to predict the density of the cocrystals, which used (six) input parameters of the component molecules. The root mean square error (RMSE) of the ANN model was 0.033, the mean absolute error (MAE) was 0.023, and the coefficient of determination (R 2) was 0.920. Model-II used the surface electrostatic potential correction method to predict the cocrystal density. The corresponding RMSE, MAE, and R 2 were 0.055, 0.045, and 0.716, respectively. The performance of Model-I is better than that of Model-II.
RESUMEN
The C(4n)H(2n)N(2n) (n = 3-8) cage molecules with D(nh) symmetry and their nitrated products, C(4n)N(4n)O(4n) (n = 3, 4, 5) and C(4n)H(n)N(3n)O(2n) (n = 4, 6, 8) were studied by DFT at the B3LYP/cc-pVDZ level. Their geometrical structures, ground-state energies, and heats of formation have been investigated. They exhibit an obvious cage effect. Hirshfeld partitioning charges in momentum space give evidence of high strained energy in the title compounds. Their orbital energy and frontier orbital shape and electrostatic potential calculation are also studied. Investigation of heat of formation and NICS analysis reveal that C(24)H(12)N(12) is the most stable molecule among title compounds with D(nh) symmetry. Their half nitrated products are predicted as a promising candidate for high energy matter.
RESUMEN
The drum-like C4nNn (n = 3-8) cages and corresponding hydrogenated products C4n H4nN2n (n = 3-8) are studied at the DFT B3LYP/6-31G** level. Their structures, energies, and vibrational frequencies have been investigated. Comparison of heat of formation reveals that C32N16 with D8h symmetry in the C4nN2n (n = 3-8) series is a promising candidate as high energy density matter. The calculation of the DeltaG and DeltaH for the hydrogenation of C4nN2n (n = 3-8) shows that it is an exothermic reaction at 298 K and the C4nH4nN2n (n = 3-8) species are more stable than C4nN2n (n = 3-8) species. The analysis of molecular orbital and selected bond lengths of N-N and C-C provides another insight about their stability. Combined with the nucleus-independent chemical shifts (NICS) calculation, it is indicated that molecular stability for cage-shaped molecules depends on not only aromatic character but also the cage effect.
RESUMEN
The liver receptor homolog-1 (LRH-1) is an important transcriptional factor in the process of cholesterol and bile acids metabolism. In this article, molecular dynamics simulation for six systems with total 60 ns is employed to study LRH-1. LRH-1/phospholipid and LRH-1/SHP (fragments) interactions are analyzed by counting atomic contact number, identifying hydrogen bonds, and estimating binding free energies (by MM-PB/SA and N-mode analysis). Through integrating our modeling result with previous experimental data, deeper understandings to LRH-1/SHP interaction are obtained, and functions of the phospholipid ligand in LRH-1 are proposed.
Asunto(s)
Simulación por Computador , Proteínas de Unión al ADN/química , Fragmentos de Péptidos/química , Fosfolípidos/química , Receptores Citoplasmáticos y Nucleares/química , Factores de Transcripción/química , Humanos , Enlace de Hidrógeno , Conformación Molecular , Movimiento (Física) , Unión Proteica , TermodinámicaRESUMEN
The farnesoid x receptor (FXR) has become a potential drug target for treating cholesterol-related and bile acid-related diseases recently. In this paper, 3-dimensional quantitative structure-activity (structure-affinity and structure-efficacy) relationships are investigated for a series of non-steroidal agonists (fexaramine series) by using the comparative molecular field analysis (CoMFA), where molecular docking method (FlexX) is employed to construct molecular superimposition maps. A proposal to design some new agonists is discussed lastly.