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  • Open access
  • 51 Reads
Copper(I) Catalyzed [3+2] Cycloaddition Reaction with Mechanistic Disparity: A DFT Study
The Huisgen [3+2] cycloaddition (32CA) reaction is one of the most useful convergent strategies for the synthesis of five membered azaheterocycles which are building the blocks for agricultural, industrial and pharmacological materials. Nonetheless, the classical 32CA reactions have certain limitations. While some 1,3 dipoles react readily with dipolarophiles without activation of either components; it is undeniable that many substrate combinations yield no cycloadducts in the absence of promoters. Besides, the control of regio- and stereochemistry is another challenge that the organic chemist encounter.   One method to enhance the reactivity and selectivity of 32CA reactions is to use metal and metalloid catalysts. In particular, transition metal catalyzed 32CA reaction, which also meets the aforementioned criteria, has emerged over the recent years as one of the most attractive synthetic techniques. Yet, a changing trend in catalyst from the rare and expensive metals (Pd, Rh, Ru) to more abundant ones (Cu, Fe, Ni) is being observed in new catalytic 32CA processes.   Studies of catalytic 32CA reaction mechanisms are not trivial because each step in the catalytic cycle is dependent on the subtle interplay between the electronic and steric effects, among others. Hence, an extensive examination of catalytic mechanism is of utmost importance, (1) to optimize reaction parameters, (2) to develop novel catalytic processes, (3) to locate and characterize competitive catalytic pathways, and (4) to enhance the understanding of fundamental reactivity. Nevertheless, synthetic approaches seldom provide a detailed picture of the catalytic 32CA reaction mechanisms and thus, quantum chemical computations which act as a complement, come to its rescue.   Indeed, Cu(I) catalyzed 32CA reaction, which comprises of several experimental studies, figure prominently in the field of organic chemistry. Moreover, based on experiments, some mechanistic postulates on the Cu(I) catalyzed 32CA reactions are available to-date. The aim of our study is to compare two particular Cu(I) 32CA catalyzed mechanisms, namely, (1) the Sharpless proposed mechanism and (2) the Katritzky's proposed mechanism at the B3LYP/6-31G(d) level of theory. An azomethine imine as dipole and a terminal alkyne as dipolarophile act as representative cycloaddition substrates to evaluate the two proposed mechanisms. The DFT study confirms that the two mechanisms studied herein is amenable to the 32CA reaction of azomethine imines and terminal alkynes. However, the reactions of azomethine imines to terminal alkynes have a kinetic preference for the mechanism proposed by Katritzky over the Sharpless one.  
  • Open access
  • 125 Reads
Synthesis of Spiro-Annelated γ-Lactams by Isocyanide-Based Multicomponent Reactions Involving Hem-Disubstituted Bifunctional Reagents
The new bifunctional hem-disubstituted alicyclic compounds IIIa-e and IVa-e were synthesized in several steps involving alkylation with allyl bromide following oxidative cleavage. Hem-disubstitues oxo-esters IIIa-e were introduced into azido-Ugi reaction followed by one-pot intramolucular bond formation to afford 3-(tetrazol-5-yl)-2-azaspiro[4.n]alkan-1-ones. The three component Ugi reaction with isocyanides, primary amines and 1-(2-oxoethyl)cycloalkanecarboxylic acids IVa-e affords spirocyclic N-substituted pyroglutamides.
  • Open access
  • 94 Reads
Designing Visfatin Inhibitors to Limit its Insulin Mimcy and Type II Diabetes.
Visfatin, otherwise known as Nicotinamide phosphoribosyltransferase (NAmPRTase or Nampt), is an adipocytokine that promotes B cell maturation and inhibits neutrophil apoptosis as well as promoting the condensation of nicotinamide. Visfatin plays an important role in promoting insulin resistance by binding to insulin receptor (IR) at a site distinct from insulin exerting a variety of insulin-mimetic effects, thereby playing a role in the development of obesity-associated insulin resistance and Type II diabetes. This research sought to understand binding interaction of pharmaceuticals to Visfatin. 11 crystal structures of the Visfatin were docked using IGEMDock to FDA, Alkaloids, Lactams, Lactones, Flavinoids, Sulfanilamide, Cyclic Imides, and NSAIDs drugs to determine structural correlation for the most effective binders. Structural similarities were determined with IGEMDock and vROCS and partition coefficient was determined using DRAGON program. This data found a cluster of potential inhibitors to Visfatin which are possible targets for Type II diabetes treatments. This research will be used in the engineering of improved Visfatin inhibitors.
  • Open access
  • 88 Reads
Synthesis of ZnO Nanorods Mmodified with TPP, TPPS and Cu-TPPS for Photodegradation of MB
In this study, ZnO nanorods have been synthesized by a simple precipitation technique with zinc nitrate as starting material in the presence of ammonium hydroxide followed by calcination at 450 ˚C. Then meso-tetrakis(4-phenyl) porphyrin (TPP), meso-tetrakis(4-sulfonatophenyl) porphyrin (TPPS), and Copper meso-tetrakis(4-sulfonatophenyl) porphyrin (Cu-TPPS) have been immobilized on the ZnO nanorods and the potential of the obtained photocatalysts in degradation of methylene blue dye was studied under UV and visible irradiation. The photocatalysts were characterized by various techniques such as XRD, SEM and FT-IR. The influence of experimental parameters on the dye photodecolorization process was studied. The role of porphyrins as sentisizers was also investigated on decolorization rate. Under these optimum conditions, the obtained decolorization efficiency for MB dye was more than 90% under visible light. The reusability of the intended catalyst was also investigated.
  • Open access
  • 111 Reads
Photocatalytic Degradation of MB from Water by Using Ni-TPPS/NiO Nanoparticles
NiO nanoparticles were synthesized by a sol-gel technique. Ni(NO3)2.6H2O and citric acid were employed as starting raw materials. Then, the obtain result calcined at 550 0C for 5 h. The phase composition and the structure of the calcined products were investigated by X-ray diffraction and scanning electron microscopy techniques, respectively. XRD patterns exhibit six (111), (200), (220), (311), (222) and (400) characteristic peaks of cubic crystalline NiO. Then The Ni-porphyrin immobilized on surface of NiO and the potential of the obtained photocatalysts in degradation of methylene blue dye was studied under visible irradiation.
  • Open access
  • 120 Reads
Photocatalytic Removing of Methylene Blue by Using of Cu-Doped ZnO, Ag-doped ZnO and Cu, Ag-codoped ZnO Nanostructures
In this study, ZnO nanorods, Silver- and copper-doped ZnO nanorods and silver, copper-doped ZnO nanorods were prepared by a simple precipitation technique. The photocatalysts were characterized by various techniques such as XRD, SEM and FT-IR. The influence of dopants content on the optical properties was investigated. It has been found that the Ag or Cu doping leads to the optical band gap narrowing. Then the potential of the obtained photocatalysts were studied on degradation of methylene blue dye under UV and visible irradiation.
  • Open access
  • 48 Reads
Designing Caspase-1 Kinase Inhibitors to Control Acute Inflammation of Orthodontic Appliances
Orthodontics is a branch of dentistry that uses tensile force from intraoral or extraoral orthodontic appliances to resolve dental malocclusions. The use of tensile force seeks to remodel periodontal ligament and alveolar bone however this process initiates acute inflammation and necrotic conditions in the periodontium. This acute inflammation arises through multiple mechanisms including that of the inflammasome conversion of pro- interleukin 1β (IL-1β) to the active form.1,2 Inhibition of one major protein found in the inflammasome, Caspase-1, has been found to block the activation of IL-1β thereby blocking the acute inflammation initiated by appliance tightening.3-5 This research sought to understand binding interaction of pharmaceuticals to the protein kinase functionality of the Caspase-1. 22 crystal structures of the kinase of the Caspase-1 protein were docked using IGEMDock to FDA, Alkaloids, Lactams, Lactones, Flavinoids, Sulfanilamide, Cyclic Imides, and NSAIDs drugs to determine structural correlation for the most effective binders. Structural similarities were determined with IGEMDock and vROCS and partition coefficient was determined using DRAGON program. This data found a cluster of approximately 10 drugs to preferentially bind to the Caspase-1 kinase for use as targeted anti-inflammatory treatments. This work will be used in the engineering of improved Caspase-1 kinase inhibitors.
  • Open access
  • 108 Reads
Photocatalytic removing of methylene blue by using of Cu-doped ZnO, Ag-doped ZnO and Cu,Ag-codoped ZnO nanostructures
Photocatalytic removing of methylene blue by using of Cu-doped ZnO, Ag-doped ZnO and Cu,Ag-codoped ZnO nanostructures In this study, ZnO nanorods, Silver- and copper-doped ZnO nanorods and silver, copper-doped ZnO nanorods were prepared by a simple precipitation technique. The photocatalysts were characterized by various techniques such as XRD, SEM and FT-IR. The influence of dopants content on the optical properties was investigated. It has been found that the Ag or Cu doping leads to the optical band gap narrowing. Then the potential of the obtained photocatalysts were studied on degradation of methylene blue dye under UV and visible irradiation. Cu and Ag doped ZnO, photocatalyst, nanorods, Methylene blue
  • Open access
  • 69 Reads
Limiting Rheumatoid Arthritis Through the Designing PI3K Protein Inhibitors
Rheumatoid arthritis (RA) is a chronic autoimmune disease that often causes inflammation of the synovial joints resulting in severe pain, bone erosion, and joint deformity which affects more than 2 million Americans. Current treatments for RA are based on anti-inflammatory treatments including steroids, non-steroidial anti-inflammatory drugs (NSAIDs), disease-modifying antirheumatic drugs (DMARDs), immunosuppressants, and TNF-alpha inhibitors. Side effects of current treatments can lead to heart problems, liver and kidney damage, bone marrow suppression, and severe lung infections. Improved pharmaceutical targeting of inflammatory proteins such as phosphphatidylinositol 3-kinase (PI3K) should yield drugs with increased efficacy and decreased side effects.1-9 This research sought to understand the pharmaceutical blockade of the PI3K kinase functionality to inhibit its function in the inflammatory pathway. 16 crystal structures of the tyrosine kinase of the PI3K protein were docked using IGEMDock to FDA approved pharmaceupticals, Alkaloids, Lactams, Lactones, Flavinoids, Sulfanilamide, Cyclic Imides, and NSAIDs drugs to determine structural correlation for the most effective binders. Structural similarities were determined with IGEMDock and partition coefficient was determined using DRAGON program. This data found a cluster of approximately 10 drugs to preferentially bind to the PI3K kinase for use as targeted anti-inflammatory treatments. This work will be used in the engineering of improved PI3K kinase inhibitors.
  • Open access
  • 85 Reads
Improving EGFR Kinase Inhibitor Design for the Targeted Treatment of Lung Cancer
With over 174,000 new cases of lung cancer being diagnosed in the United States each year novel chemotherapy treatments with efficacy towards both small-cell and non-small cell lung carcinoma is of interest to increase the survival rate of cancer patients.1,2 Historically pharmaceutical treatments have been based on surgery, radiation therapy, and broad spectrum chemotherapies. New research is now focused on targeted approaches that seek to either inhibit specific proteins necessary for cellular proliferation or to initiate apoptosis for the removal of cancerous cells. The Epithelial Growth Factor (EGF) and its Receptor (EGFR) EGFR is protein that initiates cellular growth and has been found to be overexpressed in cancer cells which makes it an effective targeted approach to cancer treatment.3-5 Specifically, this research determined structural blockade of the tyrosine kinase receptor of the EGFR as a way to inhibit cancer propagation with the use of FDA approved drugs. 22 crystal structures of the tyrosine kinase of the EGFR protein were docked using IGEMDock to 714 FDA drugs to determine structural correlation for the most effective binders. Structural similarities were determined wih IGEMDock and vROCS and partition coefficient was determined using DRAGON program. This data found a cluster of approximately 25 drugs to preferentially bind to the EGFR tyrosine kinase for use as targeted cancer treatments. This work will be used in the engineering of improved EGFR tyrosine kinase inhibitors.
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