{"id":{"repo_id":"durham","oai_identifier":"oai:etheses.durham.ac.uk:247"},"canonical_url":"https://search.dev.ndltd.org/etd/durham/oai:etheses.durham.ac.uk:247","repository":{"repo_id":"durham","name":"Durham University","base_url":"http://etheses.dur.ac.uk/cgi/oai2"},"display":{"title":"A NEW CLASS OF LUMINESCENT ORGANOMETALLICS -DIETHYNYLRHODACYCLOPENTADIENES","abstract":"The main objective in this project is to develop a greater understanding of the unusual photophysical properties of 2,5-bis(arylethynyl)rhodacyclopentadienes. Three distinct and unusual photophysical properties were found in the 2,5-bis(arylethynyl)-rhodacyclopentadienes: (i) long-lived singlet excited states, from which some of them exhibit high-intensity fluorescence with nanosecond lifetimes; (ii) slow intersystem crossing rates (k values ≈ 108 s-1) compared to typical luminescent organometallic complexes (with k values ≈ 1012 s-1); and (iii) no phosphorescence was observed even at 77 K in a rigid glass. Many photophysical experiments such as e.g. low-temperature lifetime measurments, singlet oxygen sensitisation and time-resolved infrared (TRIR) have been carried out in order to investigate further and explain the unusual photophysical properties of this class of organometallic complexes. Five different types of ligand X on 2,5-bis(p-R-arylethynyl)-X-rhodacyclopentadienes [X = 4-[4-(N,N-di-n-hexylamino)phenylethynyl]phenylethynyl- (DHAPEPE-), trimethyl silylethynyl- (TMSE-), methyl- (Me-), η2-benzoato- and acetylacetonato- (acac-)] have been synthesised and the photophysical properties of the complexes were investigated. The TMSE-rhodacyclopentadienes gave the highest fluorescence quantum yields compared to the other series of rhodacyclopentadienes. Extended phenylene-ethynylene ligands (i.e. DHAPEPE-) did not impart any effects on the max values in absorption and emission but the quantum yields were lower than those for the TMSE-rhodacyclopentadienes. η2-Benzoato- and acac- ligands shifted the max values in absorption and emission to lower energy, which implies that they induce smaller energy gaps between the excited and ground states. The emissions from the η2-benzoato-rhodacyclopentadienes were quenched (especially for those with R = H and SMe substituents, which have quantum yields of less than 0.01). The first example of isomeric biphenyl-rhodacyclopentadiene by-product formation was found in the synthesis of acac-rhodacyclopentadienes. The isomeric biphenyl-rhodacyclopentadiene by-product with R = CO2Me was isolated and its molecular structure was confirmed by X-ray analysis. Its emission spectrum shows two emission bands with max values of 394 and 544 nm in degassed toluene solution. The fluorescent emission at 394 nm has a quantum yield of 0.03, whereas the phosphorescent emission at 544 nm has a quantum yield of 0.05. The unusual long lifetime (237.6 s) of the phosphorescence at room temperature indicates that the transition is from a ligand-centred (LC)   * transition. In addition, the syntheses of 1,4-bis(p-R-phenyl)buta-1,3-diynes and novel 1,12-bis(p-R-phenyl)dodaca-1,3,9,11-tetraynes, which serve as the starting materials for the synthesis of the rhodacyclopentadienes, are also reported. Four novel 1,12-bis(p-R-phenyl)dodaca-1,3,9,11-tetraynes (where R = H, SMe, CO2Me and BMes2) have been synthesised and characterised. The formation of homo-coupling products was a major problem which reduced the yields of the 1,3,9,11-dodacatetraynes. The 1,3,9,11-dodacatetraynes were separated from their respective homo-coupling products using column chromatography, and the yields obtained were 30 – 46%.","abstract_html":"The main objective in this project is to develop a greater understanding of the unusual photophysical properties of 2,5-bis(arylethynyl)rhodacyclopentadienes. Three distinct and unusual photophysical properties were found in the 2,5-bis(arylethynyl)-rhodacyclopentadienes: (i) long-lived singlet excited states, from which some of them exhibit high-intensity fluorescence with nanosecond lifetimes; (ii) slow intersystem crossing rates (k values ≈ 108 s-1) compared to typical luminescent organometallic complexes (with k values ≈ 1012 s-1); and (iii) no phosphorescence was observed even at 77 K in a rigid glass. Many photophysical experiments such as e.g. low-temperature lifetime measurments, singlet oxygen sensitisation and time-resolved infrared (TRIR) have been carried out in order to investigate further and explain the unusual photophysical properties of this class of organometallic complexes. Five different types of ligand X on 2,5-bis(p-R-arylethynyl)-X-rhodacyclopentadienes [X = 4-[4-(N,N-di-n-hexylamino)phenylethynyl]phenylethynyl- (DHAPEPE-), trimethyl silylethynyl- (TMSE-), methyl- (Me-), η2-benzoato- and acetylacetonato- (acac-)] have been synthesised and the photophysical properties of the complexes were investigated. The TMSE-rhodacyclopentadienes gave the highest fluorescence quantum yields compared to the other series of rhodacyclopentadienes. Extended phenylene-ethynylene ligands (i.e. DHAPEPE-) did not impart any effects on the max values in absorption and emission but the quantum yields were lower than those for the TMSE-rhodacyclopentadienes. η2-Benzoato- and acac- ligands shifted the max values in absorption and emission to lower energy, which implies that they induce smaller energy gaps between the excited and ground states. The emissions from the η2-benzoato-rhodacyclopentadienes were quenched (especially for those with R = H and SMe substituents, which have quantum yields of less than 0.01). The first example of isomeric biphenyl-rhodacyclopentadiene by-product formation was found in the synthesis of acac-rhodacyclopentadienes. The isomeric biphenyl-rhodacyclopentadiene by-product with R = CO2Me was isolated and its molecular structure was confirmed by X-ray analysis. Its emission spectrum shows two emission bands with max values of 394 and 544 nm in degassed toluene solution. The fluorescent emission at 394 nm has a quantum yield of 0.03, whereas the phosphorescent emission at 544 nm has a quantum yield of 0.05. The unusual long lifetime (237.6 s) of the phosphorescence at room temperature indicates that the transition is from a ligand-centred (LC)   * transition. In addition, the syntheses of 1,4-bis(p-R-phenyl)buta-1,3-diynes and novel 1,12-bis(p-R-phenyl)dodaca-1,3,9,11-tetraynes, which serve as the starting materials for the synthesis of the rhodacyclopentadienes, are also reported. Four novel 1,12-bis(p-R-phenyl)dodaca-1,3,9,11-tetraynes (where R = H, SMe, CO2Me and BMes2) have been synthesised and characterised. The formation of homo-coupling products was a major problem which reduced the yields of the 1,3,9,11-dodacatetraynes. The 1,3,9,11-dodacatetraynes were separated from their respective homo-coupling products using column chromatography, and the yields obtained were 30 – 46%.","abstract_has_math":false,"creators":["Tay, Meng Guan"],"institution":"Durham University","degree_name":"PhD","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2010,"date_issued":"2010","date_published":"2010","updated_at":"2026-07-24T02:11:04Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Tay, Meng Guan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2010"]},{"key":"dc:date.issued","label":"Date","values":["2010"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Chemistry, Department of"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["Durham University"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://etheses.durham.ac.uk/id/eprint/247/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["PhD"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://etheses.durham.ac.uk/id/eprint/247/1/Ph.DThesis_MGTAY.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The main objective in this project is to develop a greater understanding of the unusual photophysical properties of 2,5-bis(arylethynyl)rhodacyclopentadienes. Three distinct and unusual photophysical properties were found in the 2,5-bis(arylethynyl)-rhodacyclopentadienes: (i) long-lived singlet excited states, from which some of them exhibit high-intensity fluorescence with nanosecond lifetimes; (ii) slow intersystem crossing rates (k values ≈ 108 s-1) compared to typical luminescent organometallic complexes (with k values ≈ 1012 s-1); and (iii) no phosphorescence was observed even at 77 K in a rigid glass. Many photophysical experiments such as e.g. low-temperature lifetime measurments, singlet oxygen sensitisation and time-resolved infrared (TRIR) have been carried out in order to investigate further and explain the unusual photophysical properties of this class of organometallic complexes. Five different types of ligand X on 2,5-bis(p-R-arylethynyl)-X-rhodacyclopentadienes [X = 4-[4-(N,N-di-n-hexylamino)phenylethynyl]phenylethynyl- (DHAPEPE-), trimethyl silylethynyl- (TMSE-), methyl- (Me-), η2-benzoato- and acetylacetonato- (acac-)] have been synthesised and the photophysical properties of the complexes were investigated. The TMSE-rhodacyclopentadienes gave the highest fluorescence quantum yields compared to the other series of rhodacyclopentadienes. Extended phenylene-ethynylene ligands (i.e. DHAPEPE-) did not impart any effects on the max values in absorption and emission but the quantum yields were lower than those for the TMSE-rhodacyclopentadienes. η2-Benzoato- and acac- ligands shifted the max values in absorption and emission to lower energy, which implies that they induce smaller energy gaps between the excited and ground states. The emissions from the η2-benzoato-rhodacyclopentadienes were quenched (especially for those with R = H and SMe substituents, which have quantum yields of less than 0.01). The first example of isomeric biphenyl-rhodacyclopentadiene by-product formation was found in the synthesis of acac-rhodacyclopentadienes. The isomeric biphenyl-rhodacyclopentadiene by-product with R = CO2Me was isolated and its molecular structure was confirmed by X-ray analysis. Its emission spectrum shows two emission bands with max values of 394 and 544 nm in degassed toluene solution. The fluorescent emission at 394 nm has a quantum yield of 0.03, whereas the phosphorescent emission at 544 nm has a quantum yield of 0.05. The unusual long lifetime (237.6 s) of the phosphorescence at room temperature indicates that the transition is from a ligand-centred (LC)   * transition. In addition, the syntheses of 1,4-bis(p-R-phenyl)buta-1,3-diynes and novel 1,12-bis(p-R-phenyl)dodaca-1,3,9,11-tetraynes, which serve as the starting materials for the synthesis of the rhodacyclopentadienes, are also reported. Four novel 1,12-bis(p-R-phenyl)dodaca-1,3,9,11-tetraynes (where R = H, SMe, CO2Me and BMes2) have been synthesised and characterised. The formation of homo-coupling products was a major problem which reduced the yields of the 1,3,9,11-dodacatetraynes. The 1,3,9,11-dodacatetraynes were separated from their respective homo-coupling products using column chromatography, and the yields obtained were 30 – 46%."]},{"key":"dc:format","label":"Dc Format","values":["text"]},{"key":"dc:title","label":"Title","values":["A NEW CLASS OF LUMINESCENT ORGANOMETALLICS -DIETHYNYLRHODACYCLOPENTADIENES"]}]}],"canonical_facts":{"dc:creator":["Tay, Meng Guan"],"dc:date":["2010"],"dc:date.issued":["2010"],"dc:description.abstract":["The main objective in this project is to develop a greater understanding of the unusual photophysical properties of 2,5-bis(arylethynyl)rhodacyclopentadienes. Three distinct and unusual photophysical properties were found in the 2,5-bis(arylethynyl)-rhodacyclopentadienes: (i) long-lived singlet excited states, from which some of them exhibit high-intensity fluorescence with nanosecond lifetimes; (ii) slow intersystem crossing rates (k values ≈ 108 s-1) compared to typical luminescent organometallic complexes (with k values ≈ 1012 s-1); and (iii) no phosphorescence was observed even at 77 K in a rigid glass. Many photophysical experiments such as e.g. low-temperature lifetime measurments, singlet oxygen sensitisation and time-resolved infrared (TRIR) have been carried out in order to investigate further and explain the unusual photophysical properties of this class of organometallic complexes. Five different types of ligand X on 2,5-bis(p-R-arylethynyl)-X-rhodacyclopentadienes [X = 4-[4-(N,N-di-n-hexylamino)phenylethynyl]phenylethynyl- (DHAPEPE-), trimethyl silylethynyl- (TMSE-), methyl- (Me-), η2-benzoato- and acetylacetonato- (acac-)] have been synthesised and the photophysical properties of the complexes were investigated. The TMSE-rhodacyclopentadienes gave the highest fluorescence quantum yields compared to the other series of rhodacyclopentadienes. Extended phenylene-ethynylene ligands (i.e. DHAPEPE-) did not impart any effects on the max values in absorption and emission but the quantum yields were lower than those for the TMSE-rhodacyclopentadienes. η2-Benzoato- and acac- ligands shifted the max values in absorption and emission to lower energy, which implies that they induce smaller energy gaps between the excited and ground states. The emissions from the η2-benzoato-rhodacyclopentadienes were quenched (especially for those with R = H and SMe substituents, which have quantum yields of less than 0.01). The first example of isomeric biphenyl-rhodacyclopentadiene by-product formation was found in the synthesis of acac-rhodacyclopentadienes. The isomeric biphenyl-rhodacyclopentadiene by-product with R = CO2Me was isolated and its molecular structure was confirmed by X-ray analysis. Its emission spectrum shows two emission bands with max values of 394 and 544 nm in degassed toluene solution. The fluorescent emission at 394 nm has a quantum yield of 0.03, whereas the phosphorescent emission at 544 nm has a quantum yield of 0.05. The unusual long lifetime (237.6 s) of the phosphorescence at room temperature indicates that the transition is from a ligand-centred (LC)   * transition. In addition, the syntheses of 1,4-bis(p-R-phenyl)buta-1,3-diynes and novel 1,12-bis(p-R-phenyl)dodaca-1,3,9,11-tetraynes, which serve as the starting materials for the synthesis of the rhodacyclopentadienes, are also reported. Four novel 1,12-bis(p-R-phenyl)dodaca-1,3,9,11-tetraynes (where R = H, SMe, CO2Me and BMes2) have been synthesised and characterised. The formation of homo-coupling products was a major problem which reduced the yields of the 1,3,9,11-dodacatetraynes. The 1,3,9,11-dodacatetraynes were separated from their respective homo-coupling products using column chromatography, and the yields obtained were 30 – 46%."],"dc:format":["text"],"dc:identifier.uri":["https://etheses.durham.ac.uk/id/eprint/247/1/Ph.DThesis_MGTAY.pdf"],"dc:publisher.department":["Chemistry, Department of"],"dc:publisher.institution":["Durham University"],"dc:relation.isreferencedby":["https://etheses.durham.ac.uk/id/eprint/247/"],"dc:title":["A NEW CLASS OF LUMINESCENT ORGANOMETALLICS -DIETHYNYLRHODACYCLOPENTADIENES"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["PhD"]},"updated_at":"2026-07-24T02:11:04Z"}