No description available.

No description available.

The coordination chemistry of eight chelating heterocyclic ligands is described. These ligands all contain heterocyclic ring systems with bridgehead nitrogens, and have received little attention in the literature. The ring systems examined are, specifically, imidazo[1,2-a]pyridine, imidazo[1,5-a]pyridine and triazolo[1,5-a]pyridine. The coordination complexes synthesised are mononuclear ruthenium(II) complexes, of the type [Ru(bpy)2(L)]2+. Complexes have been examined by a combination of 1H and 13C NMR, UV-visible spectroscopy, cyclic voltammetry, and X-ray crystallography, in order to study their metal-ligand interactions. A total of six complexes were analysed by single crystal X-ray diffractometry, and the resulting structures are described herein. In general, the inclusion of these ligands had the effect of raising the HOMO and lowering the LUMO, relative to the [Ru(bpy)3]2+ complex. As a result, the complexes were easier to oxidise, harder to reduce, and absorb visible light at longer wavelengths.

The novel compound VSN16R was characterised and its functional effect in the central nervous system and periphery was investigated.  VSN16R behaved as an agonist in the mouse isolated vas deferens assay.  The functional effect of VSN16R appeared to involve GPR55 and GPR18 activation. The possibility that in addition to the CB₁ receptor; the CB₂ receptor, GPR55 and GPR18 contribute towards the effects of certain cannabinoid ligands in the nervous system (both central and peripheral) was investigated.  Results suggest that the cannabinoid CB₂ receptor and also GPR55 and GPR18 are functional in the mouse vas deferens. The results imply that in addition to the CB₁ receptor, the CB₂ receptor can mediate the effects of certain cannabinoids, including CP55940, AEA and Δ⁹-THC, but not JWH015 in the [³⁵S]GTPγS assay with brain region membranes.  GPR55 can mediate the effects of certain cannabinoids, including CP55940 and JWH015 in the [³⁵S]GTPγS assay with brain region membranes.  GPR55 was also shown to mediate the effect of JWH015, but  not O-1602 in the mouse isolated vas deferens assay, indicating an additional target for O-1602 in this tissue.  Data obtained suggest that CP55940 and AEA, but not Δ⁹-THC, O-1602 or JWH015 can activate GPR18. The effect of cannabinoid ligands and VSN16R on human neutrophil migration was investigated. The functional effect of a range of phytocannabinoids and the ligand N-arachichidonoyl glycine (NAGly) at the receptor GPR902 was investigated.  The findings implied that CBD, CBG and Δ⁹-THC acid may be able to interact with GPR92 to antagonise the GPR92 agonist lysophosphatidic acid.

No description available.

No description available.

The goal of this research was to synthesize and study new phosphine crown ethers. The first target molecule was 5-phenylphoshinobis(2-hydroxy,1,3-xylyl-18-crown-5). We tried to synthesize this target molecule in six steps. 5-Bromophenol was reacted with formaldehyde, dimethylsulfate, phosphorus tribromide and tetraethylene glycol in the presence of sodium hydride producing the main intermediate molecule, 5-bromo-2-methoxy-1,3-xylyl-l8-crown-5. This molecule was reacted with n-butyllithium and dimethyl phenylphosphinite at the low temperature . NMR evidence indicated that was not obtained.The second target molecule, the oxide of 5-phenylphosphinobis(2-hydroxy-1,3-xylylcrown-5) was synthesized in nine steps. The main intermediate, 5-bromo-2-methoxy-1,3-xylyl-18-crown-5 was reacted with n-butyllithium and dimethyl phenylphosphinite to form the phosphine. This phosphine was oxidized with hydrogen peroxide. The OCH3 bond of this crown ether was cleaved by using LiI in boiling anhydrous pyridine. NMR data indicated the product was formed. / Department of Chemistry

The aza crown, sym-1,2-benzo-aza-17-crown-5, was synthesized from 6-aza-3,9-dioxa-1,11-undecanediol, and , -dibromo-o-xylene in the presence of potassium tert-butoxide. This new crown ether was reacted with 4-bromobenzyl bromide and chloroacetyl chloride to form the N-substituted 4-bromobenzyl and chloroacetyl derivatives, respectively. The aza crown and its derivatives were identified with spectroscopic data. The bidentate phosphine amine, Ph2P(CH2)3NH2, was prepared via reduction of 3-(diphenylphosphino)propionitrile by lithium tetrahydroaluminate. Schiff-base reactions between the amine group in Ph2P(CH2)3NH2 and the aldehyde group in benzaldehyde and 4-formyl-benzo-15-crown-5 provided the respective phosphine derivatives. These products were identified with spectroscopic and analytical data. Finally, palladium derivatives of these phosphine-Shiff base ligands (Ph2P(CH2)3NCHR; R = Ph, benzo-15-crown-5) were synthesized from the reactions between (Ph2CN)2PdCl2 and the ligands.

This study has resulted in a phosphine funetionalized crown ether. synrdiQ-methoxy-5-diphenylphosphino-1.3-cplyl l-24-crown-6, obtained tkmt a live step synthesis. 4-13romophenol was treated in turn with formaldehyde. di methyl sulfate, and phosphorous trihromide. producing 4-bromo-2.6-his(bromomethyl )anisole. The key intermediate. spm-di(2-methoz}-5-bromo-I.3-z( I).l )-24-crown-6. was obtained from treating 4-hromo-3.6-bis(bromomethyl )anisole with diethylenc glycol and potassium thutoyide. The potassium ion apparently provided a template to assist the formation of the product. SLm-di(2-methosp-5-diphenylphosphino- I.3-x lyl )-24-crown-6 was obtained from treating sm-di(2-methos5-5-hromo-I.3-x'kI -24-crown-6 in sequence with n-BuLi and methyldiphern I phosphinite. The nP NMR of the phosphine crown ether showed a single signal at 6 -5.35 ppm. consistent with the formation of a single product.The'1I NMR of the phosphine crown ether in chloroform-d showed signals at6354-3.56 (crown CIF). 3.61 I OCI I;I. 4.44 (benzylic Cl I.6 and 7.25-7.29 (aromatic Ii) ppm.The integrated areas were consistent with the formula. The `C NNIR of the phosphine crown ether in chloroform-d displaced signals at 6 63.1, 68.5. 70.0. 70.1. 128.5 and 128.6 (d). 128.7. 131.8 and 131.9 (d), 132.0. 133.6 and 133.7 (d). 136.1 and 136.4 (d). 137.4 and 137.5 (dl, and 158.4 ppm. The "C signals were consistent with the formula and structure. The br)minated crown ether was characterized with 'I I and ''C NMR. as well as X-ray crystallography and elemental analysis. / Department of Chemistry

Photoswitchable molecular materials are of interest for optical data storage, optically controlled electronics, and light-controlled molecular machines or ‗smart‘ surfaces. A promising way to incorporate optical switchability into materials is by using organic photochromic molecules—which convert reversibly between two forms with light—as ligands in coordination complexes. This design allows for the intimate communication between ligand and metal such that light-induced photoisomerization may be used to modulate metal-based properties. Spirooxazines, photochromic systems that photochemically isomerize between nonconjugated ring-closed spirooxazine (SO) and highly conjugated ring-opened photomerocyanine (PMC) forms, were derivatized with a phenanthroline moiety to enable the binding of transition-metal ions. Two phenanthroline–spirooxazines, an indolyl derivative and an azahomoadamantyl derivative, were investigated in the context of chemical substitution and medium effects. The ring-opened PMC forms of the spirooxazines were characterized by solid- and/or solution-state methods to extract the relative contributions of the canonical quinoidal and zwitterionic resonance forms to their molecular structure. The PMC form of the azahomoadamantyl derivative was found to exhibit significant zwitterionic character, with demonstrated sensitivity to medium polarity. The pronounced zwitterionic character was correlated with the high stability of the PMC form, high photoresponsivity, and slow thermal relaxation rates in this class of spirooxazines. The relative ligand field strengths of the SO and PMC forms of the two phenanthroline–spirooxazines were analyzed using the FT-IR and 13C NMR carbonyl signals of their molybdenum–tetracarbonyl– spirooxazine complexes. Differences in metal–ligand bonding in the SO and PMC forms were also investigated by a density functional theory fragment molecular orbital analysis. The SO form was found to be a better π-acceptor both empirically and theoretically. Lastly, the spirooxazine ligands were incorporated into electronically bistable cobalt– dioxolene redox isomers, where the low-spin-CoIII/high-spin-CoII equilibrium is sensitive to ligand field strength. Using solution-state spectroscopic methods, it was shown that the redox state of the cobalt centre could be modulated through photoisomerization of the spirooxazine ligand. As changes in cobalt redox state are associated with changes in magnetic spin state, this system forms the basis for a room-temperature photomagnetic material and highlights the powerful role of photochromic phenanthroline–spirooxazine ligands in developing photoswitchable multifunctional materials. / Graduate / 0485