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Thesis (Ph.D.) - University of Glasgow, 2007. / Ph.D. thesis submitted to the Department of Chemistry, University of Glasgow, 2007. Includes bibliographical references. Print version also available.

No description available.

Conventional xanthene dyes (eg: fluorescein and rhodamine) have their absorptions and emissions in the visible region, which limits their use in cellular imaging. Absorptions and emissions at longer wavelengths allow for low background cellular autofluorescence, deep tissue penetration, and minimum cell damage. Chapter I discusses the background of fluorescent dyes and the importance of near-infrared (NIR) emissive dyes for biological applications. Chapter II is based on the design and synthesis of new xanthene-based NIR I dyes using simple and short synthetic routes. This study used pyrrole and indole as donor molecules and combined them to the xanthene core by the Suzuki cross-coupling reaction to prepare the new dyes. After the treatment with trifluoroacetic acid, these new dyes transformed from their non-fluorescent to fluorescent forms and exhibited excellent red shifts in their maximum absorption and emission wavelengths. The novel pyrrole-based xanthene dye was used to investigate the efficacy of the dye as a probe for fluoride ions. We were able to modify this dye with a silyl ester receptor and develop a probe as a colorimetric turn-off fluoride ion sensor. In chapter III, we describe the synthesis of different NIR emissive xanthene dyes using the donor-acceptor-donor concept. New xanthene-based dyes were designed with five-membered heterocycles and fused heteronuclear molecules. Additionally, xanthene-based dyes containing an alkyne spacer were synthesized using the D-pi-A model to extend the pi-conjugation through the alkyne spacer. All of the dyes exhibited absorption and emission maxima in the visible to NIR I region, between 500-850 nm. In chapter IV, we discussed the synthesis of xanthene-based electrochromic materials. These compounds used xanthene as the chromophore and ferrocene as the electrophore units. Novel rhodamine-based symmetric and unsymmetric dyes were synthesized by attaching the ferrocene unit through the lactam ring. The compounds were then investigated as an electrochromic probe using UV-Vis, cyclic voltammetry, and spectroelectrochemical analysis.

This study experiments with the methods of 1-(4, 4'-Dinitrodiphenylmethyl)-Piperidines; 1-(4-Nitrobenzyl)-and 1-(4-Nitrobenzoyl)-Piperdines.

Guo, Jia. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 126-156). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

This thesis is concerned with the synthesis of functionalised piperidines. The piperidine unit is found in numerous alkaloids and other natural products, and has also been incorporated into synthetic compounds of significant therapeutic or strategic synthetic potential. Although numerous syntheses of individual piperidine compounds have been published, there are few general routes to this class of compounds, and there is therefore a need for such routes to be developed. Bicyclic lactams derived from (S)-pyroglutamic acid have been shown to be useful synthons in the synthesis of pyrrolidines. An analogous bicyclic lactam was therefore synthesised from (S)-lysine. Alkylations at the carbon atom a- to the lactam carbonyl group were studied in detail. A number of different groups could be introduced in good to excellent yield, and with moderate to good stereoselectivity. The selectivity of these reactions was believed to depend on the shape of the bicyclic system, and a stereoelectronic effect of the nitrogen lone pair. The bicyclic lactam was further elaborated to an activated enone. This was shown to be relatively unreactive to cycloaddition reactions. It is believed that this is because the activating ester group is not conjugated with the carbon-carbon double bond. However, conjugate addition could be achieved in high yield and excellent stereoselectivity using a zinc enolate Reformatsky reagent. An epoxide could also be formed in excellent yield and with excellent stereoselectivity. The Reformatsky adduct was shown to be a suitable substrate for a Pb(IV)-mediated arylation reaction. Examples of the functionalised lactams were deprotected to give hydroxymethyl piperidinones and cyclic amino acids. This route therefore allows access to the desired novel compounds.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1933. / Typescript. With this are bound 2 reprints from Journal of the American Chemical Society: The reaction of organic halides with piperidine : III. Cyclohexyl bromide and the butyl bromides / By W.V. Drake and S.M. McElvain. Vol. 55 (1933), p. 1155-1158 -- The reaction of organic halides with piperidine : IV. Bromo esters / By W.V. Drake and S.M. McElvain. Vol. 56 (1934), p. 697-700. Includes bibliographical references (leaves 54-55).

Submitted in complete fulfillment for the Degree of Master of Applied Sciences in Biotechnology, Durban University of Technology, Durban, South Africa, 2016. / Piperidine derivatives are essential heterocyclic compounds that have beneficial roles in the medical and commercial sector. They can be isolated from plant material and can be chemically synthesised using simple cost efficient methods. Piperidines and their derivatives are clinically used to prevent postoperative vomiting, facilitate radiological evaluation, correct gastrointestinal function as well as speed up gastric emptying before anaesthesia. Piperidine derivatives also demonstrate a wide spectrum of biological activities which include; antimicrobial, anticancer, anti- TB, anti-HIV, anti-inflammatory, analgesic, anti-influenza, anti-inflammatory and antitumor activity. The properties of piperidine derivatives depend on the nature of the side chains and their orientation. Based on the promising data that demonstrated the synergistic effects of biological agents with piperidine derivatives, the aim of our research is to determine the pharmacological activities, i.e. (i) antimicrobial activity, (ii) anti-inflammatory, (iii) anti-oxidant activity, (iv) cytotoxicity, and (v) biosafety of six piperidine derivatives, PM1 to PM6. All six piperidine derivatives (PM1-PM6) screened for antimicrobial activity exhibit characteristics of varying degrees of microbial inhibition against some Gram-positive and Gram-negative bacteria (B. cereus, B. subtilis, E. coli, S. aureus, Kl. Pneumonia, M. liuteus and P. aurenginosa) with the exception of B. polymixa, S. marcescens and S. faecalis. Certain piperidine derivatives did not demonstrate high inhibition activity towards the fungal strains, with inhibition only shown against four fungal species; A. niger, A. flavus, C. albicans and S. cerevisiae. Thus it is proposed that minor changes could be made to the structure of the compounds so that they can alter the effect that the compounds have on the specific fungi strains. With regard to antioxidant activity it is noted that the concentrations of the test compounds are directly proportional to the percentage of scavenging capacity. In comparison of the piperidine derivatives (PM1-PM6) to Rutin (reference standard), it was illustrated that Rutin displayed the best antioxidant activity. All six piperidine derivatives (PM1-PM6) showed greater than 50% anti-inflammatory activity, whilst the anti-inflammatory reference standard NCGA displayed the greatest activity in comparison to the piperidine derivatives tested. The safety of the piperidine derivatives was tested by assaying cytotoxicity, against melanoma, MCF7 cancer cells and normal fibroblasts as well as Brine shrimp lethality assay. All piperidine derivatives demonstrated high cytotoxicity activity against both cancer cell lines (melanoma and MCF7) and around 50 – 52% cytotoxicity against healthy cells. Chloro substitution of the phenyl ring increases cytotoxicity of compounds (Aerluri et al., 2012). This compound can be used in the treatment of cancer cells while inhibiting 50% of normal cells. All six piperidine derivatives (PM1-PM6) were also tested for toxicity against Artemia salina in a brine shrimp lethality assay. Piperidine derivatives exhibited varying degree of toxic activity towards the shrimp, with all derivatives displaying ± 50% toxic activity at 1000 µg/mL. These results reveal a directly proportional relationship between concentration of drug and toxicity. It remains a future research objective to modify these piperidine compounds (PM1-PM6) chemically to produce more derivatives for further biological evaluation. All the studied piperidine compounds have possible leads for optimization to carry out pre-clinical trials. We can conclude that the substitution of different side chains on the piperidine nucleus results in varying degree of pharmacological activity. Also, compounds containing the substitution of a chloro group at position 4 and a fluoro group at position 2 on the phenyl ring attached to carbon 2 and 6 on the piperidine nucleus resulted in high pharmacological activity. This good pharmacological activity was also exhibited by compounds containing substitutions of a methoxy group at position 3 on the phenyl ring attached to carbon 1 and 6 on the piperidine nucleus. Compounds containing a methoxy group positioned at carbon 4 on the phenyl ring which is attached to carbon 1 and 4 on the piperidine nuleus presented low pharmacological activity. Low activity was also exhibited by compounds containing substitution of a cyano group at position 4 on the phenyl ring which is attached to carbon 2 and 6 on the piperidine ring and a methyl group at position 4 on the phenyl group attached to a nitrogen at position 1 on the piperidine nucleus. / M