5.2 Literature survey Vaquero et al. have extensively work on heteroaromatic cation and they have fruitfully established compounds 5.1 and 5.2 by condensation of [1,4]-dioxane-2,3-diol (DODO) or acenaphthenequinone with the corresponding N-aminoazinium or azolium salts in presence of triethylamine and DMF as solvent (Scheme 5.1).31 The compounds have been studied in order to gain insights into the effect of the size, shape and charge distribution on the fluorescence, DNA interactions and DNA sequence selectivity properties. Scheme 5.1 Synthesis of quinolizinium derivatives Gallagher et al. has established a library of compounds on 6-6 fused bicyclic pyridine. Here 2, 6-difluoropyridine 5.3 underwent nucleophilic substitution with 3-amino-1-propanol to provide 5.4 in 95% yield. It was mesylated and cyclized to give the pyridinium salt 5.5 and eventually mild basic hydrolysis of 5.5 furnished 5.6 in 85% yield (Scheme 5.2).32 …show more content…
Scheme 5.2 N-bridgehead 6-6 fused bicyclic pyridone (via Mitsunobu route) Very recently, the efficient green methodology for the synthesis of substituted 4H-pyrido[1,2-a]pyrimidines 5.7, by utilising 2-aminopyridine, cyclohexane carbaldehyde 5.8 and 2-phenylacetaldehyde 5.9 under admicellar catalysis by sulphur nanoparticles (Scheme
The percent yield of products that was calculated for this reaction was about 81.2%, fairly less pure than the previous product but still decently pure. A carbon NMR and H NMR were produced and used to identify the inequivalent carbons and hydrogens of the product. There were 9 constitutionally inequivalent carbons and potentially 4,5, or 6 constitutionally inequivalent hydrogens. On the H NMR there are 5 peaks, but at a closer inspection of the product, it seems there is only 4 constitutionally inequivalent hydrogens because of the symmetry held by the product and of this H’s. However, expansion of the peaks around the aromatic region on the NMR show 3 peaks, which was suppose to be only 2 peaks. In between the peaks is a peak from the solvent, xylene, that was used, which may account to for this discrepancy in the NMR. Furthermore, the product may have not been fully dissolved or was contaminated, leading to distortion (a splitting) of the peaks. The 2 peaks further down the spectrum were distinguished from two H’s, HF and HE, based off of shielding affects. The HF was closer to the O, so it experienced more of an up field shift than HE. On the C NMR, there are 9 constitutionally inequivalent carbons. A CNMR Peak Position for Typical Functional Group table was consulted to assign the carbons to their corresponding peaks. The carbonyl carbon, C1, is the farthest up field, while the carbons on the benzene ring are in the 120-140 ppm region. The sp3 hybridized carbon, C2 and C3, are the lowest on the spectrum. This reaction verifies the statement, ”Measurements have shown that while naphthalene and benzene both are considered especially stable due to their aromaticity, benzene is significantly more stable than naphthalene.” As seen in the reaction, the benzene ring is left untouched and only the naphthalene is involved in the reaction with maleic
Fluorescence measurement provides very important information about the photochemistry of a particular molecule. The first part of this experiment was dealing with the fluorescence behavior of a Leucophor PAF. Information from both spectrophotometry and fluorimetry was used to measure the quantum yield as well as to explain why Leucophor PAF was use as commercial optical brightener. The second part of this experiment dealing with fluorescence quenching of quinine bisulphate solution (QBS) is the presence of sodium chloride.
Compounds resulting from heterocyclic chemistry form a huge family of variations of organic compounds with cyclic or acyclic structures having carbons and at least another element with the most common being sulfur, oxygen, fluorine or nitrogen 49. Such heterocyclic compounds must have their rings having heteroatoms and the rings could be unsaturated or saturated as well 1. These compounds are usually classified as aromatic or alicyclic heterocycles 6. The latter contain cyclic analogues of thioethers, ethers and amines 6. It has been studied before that the families of nitrogen- sulfur heterocycles have aromatic compounds that are very stable19. Also, fluorinated compound using trifluoromethyl group is often used to reduce in vivo metabolism of potential drugs, in addition to improving cellular membrane permeability (LogP)88. Sulfur and Nitrogen organic compounds heterocycles are basically drawn from aromatic heterocycles realized when a heteroatom occupies the position of a carbon atom in the ring of an organic aromatic
The challenging synthetic feature of Salvileucalin B is that is possesses a stable norcaradiene core fixed within a polycylic skeleton.2 The heart of the synthetic appeal is the norcaradiene core. This six membered diene ring fused to a fully substituted cyclopropane is a puzzle for synthetic chemists. Structures of this type often rearrange to seven-membered cycloheptatriene rings, but in this case, the polycyclic framework around it stabilizes it. Studies have shown that due to the geometrical constrains, the norcaradiene is stable at room temperature,11 which means that the electrocyclic ring-opening of the norcaradiene core would result in two bridgehead olefins within a strained [4.3.1] bicycle, which is highly unfavorable.12 This norcaradiene core of Salvileucalin B is also decorated with two γ-lactones, a furan moiety and two tertiary carbon stereocenters. The formation of the stable norcaradiene demands the construction of a fully substituted cyclopr...
The study of nucleic acids has now become a fruitful and dynamic scientific enterprise. Nucleic acids are of unique importance in biological systems. Genes are made up of deoxyribonucleic acid or DNA, and each gene is a linear segment, or polymer, of a long DNA molecule. A DNA polymer, or DNA oligonucleotide, contains a linear arrangement of subunits called nucleotides. There are four types of nucleotides. Each nucleotide has three components; a phosphate group, a sugar and a base that contains nitrogen within its structure. The sugar moiety in DNA oligonucleotides is always dexoyribose, and there are four alternative bases: adenine (A), thymine (T), guanine (G), and cytosine (C). The phosphate groups and the deoxyribose sugars form the backbone of each DNA stand. The bases are joined to the deoxyribose sugar and stick out to the side. Both oligomers, DNA and RNA, consist of 5’->3’ phosphodiester-linked nucleotide units that are composed of a 2’-deoxy-D-ribose (DNA) or D-ribose (RNA) in their furanose forms and a heteroaromatic nucleobase (A, T, G, and C; A, U, G, C), and the resulting oligonucleotide chain is composed of a polar, negatively charged sugar-phosphate backbone and an array of hydrophobic nucleobases. The amphiphilic nature of these polymers dictates the assembly and maintenance of secondary and tertiary structures the oligonucleotides can form. In the DNA duplex structure, genetic information is stored as a linear nucleotide code. This code can be accessed and replicated. RNA, or ribonucleic acid, is another structurally related essential biopolymer. RNA differs from DNA in having the sugar ribose in place of the deoxyribos...
The Diels-Alder experiment was conducted in laboratory to produce a bridged polycyclic anhydride. The Diels-Alder reaction takes place to combine a diene; the electron rich nucleophile with a dienophile which is “diene loving”, with at least one strong electron-withdrawing group1. In this experiment, anthracene is used as the diene which combines with maleic anhydride, the dienophile, to form
Deoxyribo Nucleic Acid (DNA) is a chromosome found in the nucleus of a cell, which is a double-stranded helix (similar to a twisted ladder). DNA is made up of four bases called adenine (A), thymine (T), guanine (G), and cytosine (C), that is always based in pairs of A with T and G with C. The four bases of A, C, G, and T were discovered by Phoebus Levene in 1929, which linked it to the string of nucleotide units through phosphate-sugar-base (groups). As mention in Ananya Mandal research paper, Levene thought the chain connection with the bases is repeated in a fix order that make up the DNA molecu...
Chemistry dictates the structure of DNA. DNA is a polymer of monomers called nucleic acids. These are made of a nitrogenous base, a phosphate group and a sugar. It is the negative charge on the phosphate group that makes DNA an acid. There are 4 different bases: adenine, thymine, guanine and cytosine. In groups of three, these four bases can code for any protein coded for in an organism’s genome. Two strands of nucleic acids stack on top of each other in a double helix. The backbone of the nucleic acids consists of the interaction between phosphate groups and the hydroxide groups of nucleic acids. These are held together by covalent bonds called phosphodiester bonds. The helix itself is held together by hydrogen bonds. Although h...
Recently, several chemical synthetic cross-linkers have also been developed having superior cross-linking properties [27]. In particular, 4-aminoethanol-N-hydroxyethanyl-1,8- naphthalimide (AHN), a dual-hydroxyl naphthalimide derivative that have been utilized in fluorescent labeling and as the chemical cross-linking agent but with less toxicity [28].
...Coauthor, ChemBioChem 2006, 7, 1-10; b) A. Author, B. Coauthor, Angew. Chem. 2006, 118, 1-5; Angew. Chem. Int. Ed. 2006, 45, 1-5.))
Connected to the backbone of the DNA molecule are different combinations of the four base pairs: adenine, cytosine, guanine and thynime - where only thymine and adenine pair together, and cytosine with guanine. The combination of a sugar molecule, a base and a phosphate molecule grouped together make a nucleotide. When the sugar is linked to the phosphate, it makes up the one side of the DNA. These nucleotides are found in abandantly.
The objective of this research is to synthesize the compound 3-diazonium-4-(trifluorovinyloxy)-perfluorobutanesulfonyl fluoride zwitterion for polymerization and use as the electrolyte in Proton Exchange Membrane (PEM) fuel cells. As cleaner energy sources, PEM fuel cells produce 90% less pollution than fossil fuels. The target monomers are hypothesized to have three major components, these components are an aryl diazonium zwitterion, an aryl perfluoro vinyl ether moiety and a perfluoroalkyl (aryl) sulfonamide pendant. In addition, the compound’s perfluoroalkyl backbone increases the thermal and chemical stability and can increase the proton conductivity of the polymer. The diazonium zwitterion should chemically bond the monomer or polymer
In this experiment the absorbance of DNA (7.5×10-5 M) at 260 nm was monitored with gradual increase in temperature from 25-950C in the presence and absence of the compound 4NCO (4×10-5 M).The absorbance values of DNA and drug was normalized and plotted as a function of temperature to obtain Tm. Tm of DNA in both the condition was obtained from the midpoint of the melting curve. This absorbance vs. temperature curve was differentiated and weighted maximum was taken as Tm Ghosh and
The molecules which perform the recognition are known as host molecules, and those which are recognized are termed guest molecules. The double stranded DNA, as an excellent example, can be review as complementary molecular recognition by molecular self-assembly through matched base pairs (complementary base pairing) on adjacent strands, hydrophobic effects and π-π stacking. Therefore, molecular recognition chemistry is also called host–guest chemistry that can exhibit molecular
Since the first synthetic path for the formation of porphyrins was reported in the 1930s by Fisher1 and Rothemund2 simultaneously, extensive studies regarding coordination, polymerization and porphyrin modifications in the meso and β positions have been reported. These gives a lot of room to tailor the porphyrins so that they feature the desired properties. Porphyrins drawn the attention of scientist in many fields: artificial enzymes, catalytic reactions, organic photovoltaics and molecular electronics.