title: Studies on the coordination chemistry of functionalised thiourea ligands

authors: Risi, Matthew

abstract: This thesis explores the coordination chemistry of functionalized thiourea ligands with electron-withdrawing sulfonyl, phosphoryl and diacyl substituents. These ligands, despite their structural similarity to acylthioureas, exhibit unique coordination behaviours that have been largely understudied within the literature, particularly with platinum group and related late transition metals. By utilizing a series of characterization techniques, including single-crystal X-ray diffraction, electrospray ionization mass spectrometry, NMR spectroscopy, and computational methods, this work aimed to establish foundational knowledge to inform future application-driven research within this research domain.

Firstly, dianionic sulfonylthiourea ligands were investigated towards platinum(II), revealing a distinct preference for distal isomer (coordinated via S,N-sulfonyl) which was found to be a result of a stabilizing chalcogen bond between thiourea sulfur and sulfonyl oxygen atoms. This non-covalent interaction, confirmed computationally and crystallographically, highlights the potential for modulating isomer selectivity of thiourea ligands through ligand design. Following this study, Chapter 3 extends the investigation of dianionic and monoanionic sulfonylthiourea ligands to organometallic ruthenium(II), iridium(III), and rhodium(III) in the piano stool arrangement. The resulting complexes demonstrated how steric factors influence isomerization and resulting coordination modes. While the proximal isomer persisted among the prepared complexes, using sufficient steric bulk around the metal centre, the distal isomer was formed, exhibiting proximal to distal isomerization in the liquid state. Anticancer assessments against various human cancer cell lines were performed externally which show moderate activity. Trends indicating enhanced efficacy through increased ligand lipophilicity were observed among the ruthenium(II) complexes. In Chapter 4, platinum(II) complexes with dianionic phosphorylthiourea ligands are characterized, revealing a consistent distal isomer preference modulated by bulky substituents. The inclusion of phosphorus atoms onto the ligand enhances characterization capabilities over similar ligands via ³¹P{¹H} NMR spectroscopy, providing a robust tool for elucidating coordination modes. Chapter 5 introduces symmetric diacylated thioureas as versatile ligands for platinum(II), palladium(II), and gold(III). Their coordination mode, forming four-membered S,N coordinated metallocycles, contrasts with the related monoacylated acylthiourea analogues. Moreover, the inclusion of a second acyl group onto the thiourea core allows for additional chalcogen and hydrogen bonding interactions which dominate the structure of the complex. Finally, Chapter 6 presents a ruthenium cymene complex featuring a neutral monodentate diacylthiourea ligand. Non-covalent interaction analysis identifies chalcogen and hydrogen bonding as determining the structural arrangement, reinforcing the importance of these features in future applications. 
Collectively, this thesis provides a comprehensive foundation for understanding the coordination chemistry of functionalized thiourea ligands bearing electronegative substituents, opening avenues for their tailored use in fields ranging from catalysis to medicinal chemistry.

text: Studies on the coordination chemistry of functionalised thiourea ligands This thesis explores the coordination chemistry of functionalized thiourea ligands with electron-withdrawing sulfonyl, phosphoryl and diacyl substituents. These ligands, despite their structural similarity to acylthioureas, exhibit unique coordination behaviours that have been largely understudied within the literature, particularly with platinum group and related late transition metals. By utilizing a series of characterization techniques, including single-crystal X-ray diffraction, electrospray ionization mass spectrometry, NMR spectroscopy, and computational methods, this work aimed to establish foundational knowledge to inform future application-driven research within this research domain.

Firstly, dianionic sulfonylthiourea ligands were investigated towards platinum(II), revealing a distinct preference for distal isomer (coordinated via S,N-sulfonyl) which was found to be a result of a stabilizing chalcogen bond between thiourea sulfur and sulfonyl oxygen atoms. This non-covalent interaction, confirmed computationally and crystallographically, highlights the potential for modulating isomer selectivity of thiourea ligands through ligand design. Following this study, Chapter 3 extends the investigation of dianionic and monoanionic sulfonylthiourea ligands to organometallic ruthenium(II), iridium(III), and rhodium(III) in the piano stool arrangement. The resulting complexes demonstrated how steric factors influence isomerization and resulting coordination modes. While the proximal isomer persisted among the prepared complexes, using sufficient steric bulk around the metal centre, the distal isomer was formed, exhibiting proximal to distal isomerization in the liquid state. Anticancer assessments against various human cancer cell lines were performed externally which show moderate activity. Trends indicating enhanced efficacy through increased ligand lipophilicity were observed among the ruthenium(II) complexes. In Chapter 4, platinum(II) complexes with dianionic phosphorylthiourea ligands are characterized, revealing a consistent distal isomer preference modulated by bulky substituents. The inclusion of phosphorus atoms onto the ligand enhances characterization capabilities over similar ligands via ³¹P{¹H} NMR spectroscopy, providing a robust tool for elucidating coordination modes. Chapter 5 introduces symmetric diacylated thioureas as versatile ligands for platinum(II), palladium(II), and gold(III). Their coordination mode, forming four-membered S,N coordinated metallocycles, contrasts with the related monoacylated acylthiourea analogues. Moreover, the inclusion of a second acyl group onto the thiourea core allows for additional chalcogen and hydrogen bonding interactions which dominate the structure of the complex. Finally, Chapter 6 presents a ruthenium cymene complex featuring a neutral monodentate diacylthiourea ligand. Non-covalent interaction analysis identifies chalcogen and hydrogen bonding as determining the structural arrangement, reinforcing the importance of these features in future applications. 
Collectively, this thesis provides a comprehensive foundation for understanding the coordination chemistry of functionalized thiourea ligands bearing electronegative substituents, opening avenues for their tailored use in fields ranging from catalysis to medicinal chemistry.

year: 2025-01

title: Utility Exchanger Network Design for Non-Isothermal Utility Considering Process Control

authors: Tarighaleslami, Amir Hossein

abstract: This paper investigates a preliminary control strategy based on bypass control loop of Utility Exchangers Network (UEN) for non-isothermal utilities in a Total Site Heat Integration (TSHI) system. Few details on the design and control of non-isothermal utility systems, e.g. hot water loops, that includes Total Site heat recovery are presented in the literature. Heat Exchanger Networks (HEN) can be considered as a combined Heat Recovery Network (HRN) and UEN for each individual processes within the Total Site. Control strategy presented in the current paper are based on the control of utility side in a process – utility heat exchanger match to control process stream target temperature and analyse Total Site (TS) utility system in a Process Integration point of view. Bypass control has been used in the research. A Hot Water loop as representative of a large industrial plant utility system is studied as a case study. The process stream segment target temperature to be achieved and process stream segment supply temperature and flow rate may vary up to ±15 %. The HW utility temperature in the loop is controlled by using indirect heat transfer from higher and lower level utility and by using HW loop bypass. A 24 h period has been considered for the study. Results show that the HW utility loop has a 2.4 MW heat deficit in time-average condition. By controlling the HW utility loop using the proposed heuristics, utility heating requirement may vary between 0.7 to 3.5 MW, which is supplied by the Low Pressure steam main.

text: Utility Exchanger Network Design for Non-Isothermal Utility Considering Process Control This paper investigates a preliminary control strategy based on bypass control loop of Utility Exchangers Network (UEN) for non-isothermal utilities in a Total Site Heat Integration (TSHI) system. Few details on the design and control of non-isothermal utility systems, e.g. hot water loops, that includes Total Site heat recovery are presented in the literature. Heat Exchanger Networks (HEN) can be considered as a combined Heat Recovery Network (HRN) and UEN for each individual processes within the Total Site. Control strategy presented in the current paper are based on the control of utility side in a process – utility heat exchanger match to control process stream target temperature and analyse Total Site (TS) utility system in a Process Integration point of view. Bypass control has been used in the research. A Hot Water loop as representative of a large industrial plant utility system is studied as a case study. The process stream segment target temperature to be achieved and process stream segment supply temperature and flow rate may vary up to ±15 %. The HW utility temperature in the loop is controlled by using indirect heat transfer from higher and lower level utility and by using HW loop bypass. A 24 h period has been considered for the study. Results show that the HW utility loop has a 2.4 MW heat deficit in time-average condition. By controlling the HW utility loop using the proposed heuristics, utility heating requirement may vary between 0.7 to 3.5 MW, which is supplied by the Low Pressure steam main.

year: 2018

title: Mātauranga Māori to inform understanding of population dynamics and health of pipi in Waihī Estuary, Bay of Plenty.

authors: Kettle, Tyla

abstract: Estuaries are among the most productive ecosystems on earth. They hold significant value to Māori as they connect the whenua (land), awa (river) and moana (ocean), and are an important source of kaimoana (seafood) including shellfish. However, due to increased anthropogenic pressures, many estuaries are degraded, affecting taonga (Māori treasure) species such as pipi (Paphies australis). My thesis uses kaupapa Māori methodology and is co-developed with Ngāti Whakahemo, tangata whenua (people of the land) of Waihī Estuary. This project fundamentally draws upon mātauranga Māori (traditional Māori knowledge), combined with western science to map the historic and current distribution, abundance and health of pipi in Waihī Estuary; as well as explore the perceptions of threats to pipi and estuary ecology from tangata whenua and the regional authority. 
Participatory mapping was used via kōrero/interviews with kaumātua to identify sites of significance for pipi, which were then sampled in November 2020. Mātauranga ā iwi from Ngāti Whakahemo informed the sampling locations. Previous pipi sampling methodology and protocols undertaken by the Ministry for Primary Industries (MPI) were used to facilitate temporal comparisons of pipi distribution and abundance. Environmental factors including sediment grain size, organic content, total nitrogen (TN) and total phosphorus (TP) were also measured to help understand what drives the population dynamics of pipi. Perceptions of tangata whenua and staff members of the Bay of Plenty Regional Council (BOPRC) were also explored following methods similar to Klain et al. (2018) and implementing a dread risk tool via participatory mapping.
Results show that culturally significant sites identified by kaumātua support high pipi abundances of large size (40mm+), with low abundances of pipi in the upper reaches of the estuary. The inclusion of sites identified by MPI allowed for more comprehensive survey on pipi population dynamics by utilising a stratified survey design. Pipi size and abundance was significantly correlated with environmental factors with high pipi densities associated with medium grain size fractions and low levels of TN, TP and organic content. Over harvesting was perceived by kaumātua and BOPRC staff members as the dominant threat to pipi abundance and Waihī Estuary. Nutrients related to sewage inputs and runoff were rated as the second highest perceived threat and diseased shellfish ranked third by kaumātua and BOPRC staff members. 
This study demonstrates that the sharing of mātauranga ā iwi can fundamentally inform western science methods and can be used as an approach to research in the marine science realm. The research space was shared by researchers and kaumātua, was honourable of the mātauranga, iwi voices were heard and a co-developed field survey plan/research plan was produced. Iwi concerns were made a priority throughout, and incorporated into the monitoring, mapping and management frameworks. Thus, I had a Māori-centred agenda which is important as Ngāti Whakahemo are looking to utilise the results from my research to inform their iwi environmental management plan. This approach will help to strengthen current marine management practices and in turn Aotearoa New Zealand’s ecosystems due to iwi environmental management plans being informed by such results.

text: Mātauranga Māori to inform understanding of population dynamics and health of pipi in Waihī Estuary, Bay of Plenty. Estuaries are among the most productive ecosystems on earth. They hold significant value to Māori as they connect the whenua (land), awa (river) and moana (ocean), and are an important source of kaimoana (seafood) including shellfish. However, due to increased anthropogenic pressures, many estuaries are degraded, affecting taonga (Māori treasure) species such as pipi (Paphies australis). My thesis uses kaupapa Māori methodology and is co-developed with Ngāti Whakahemo, tangata whenua (people of the land) of Waihī Estuary. This project fundamentally draws upon mātauranga Māori (traditional Māori knowledge), combined with western science to map the historic and current distribution, abundance and health of pipi in Waihī Estuary; as well as explore the perceptions of threats to pipi and estuary ecology from tangata whenua and the regional authority. 
Participatory mapping was used via kōrero/interviews with kaumātua to identify sites of significance for pipi, which were then sampled in November 2020. Mātauranga ā iwi from Ngāti Whakahemo informed the sampling locations. Previous pipi sampling methodology and protocols undertaken by the Ministry for Primary Industries (MPI) were used to facilitate temporal comparisons of pipi distribution and abundance. Environmental factors including sediment grain size, organic content, total nitrogen (TN) and total phosphorus (TP) were also measured to help understand what drives the population dynamics of pipi. Perceptions of tangata whenua and staff members of the Bay of Plenty Regional Council (BOPRC) were also explored following methods similar to Klain et al. (2018) and implementing a dread risk tool via participatory mapping.
Results show that culturally significant sites identified by kaumātua support high pipi abundances of large size (40mm+), with low abundances of pipi in the upper reaches of the estuary. The inclusion of sites identified by MPI allowed for more comprehensive survey on pipi population dynamics by utilising a stratified survey design. Pipi size and abundance was significantly correlated with environmental factors with high pipi densities associated with medium grain size fractions and low levels of TN, TP and organic content. Over harvesting was perceived by kaumātua and BOPRC staff members as the dominant threat to pipi abundance and Waihī Estuary. Nutrients related to sewage inputs and runoff were rated as the second highest perceived threat and diseased shellfish ranked third by kaumātua and BOPRC staff members. 
This study demonstrates that the sharing of mātauranga ā iwi can fundamentally inform western science methods and can be used as an approach to research in the marine science realm. The research space was shared by researchers and kaumātua, was honourable of the mātauranga, iwi voices were heard and a co-developed field survey plan/research plan was produced. Iwi concerns were made a priority throughout, and incorporated into the monitoring, mapping and management frameworks. Thus, I had a Māori-centred agenda which is important as Ngāti Whakahemo are looking to utilise the results from my research to inform their iwi environmental management plan. This approach will help to strengthen current marine management practices and in turn Aotearoa New Zealand’s ecosystems due to iwi environmental management plans being informed by such results.

year: 2021