title: Further studies on the dialkylation chemistry of [Pt₂(μ-S)₂(PPh₃)₄] with activated alkyl halides RC(O)CH₂X (X = Cl, Br)

authors: Ujam, Oguejiofo Theophilus

subjects: Dinuclear platinum complexes

abstract: Further studies have been carried out into the reactivity of [Pt₂(μ-S)₂(PPh₃)₄] towards a range of activated alkylating agents of the type RC(O)CH₂X (R = organic moiety e.g. phenyl, pyrenyl; X = Cl, Br). Alkylation of both sulfide centres is observed for PhC(O)CH₂Br, 3-(bromoacetyl)coumarin [CouC(O)CH₂Br], and 1-(bromoacetyl)pyrene [PyrC(O)CH2Br], giving dications [Pt₂{μ-SCH₂C(O)R}₂ (PPh₃)₄] ²⁺, isolated as their PF₆⁻ salts. The X-ray structure of [Pt₂{μ-SCH₂C(O)Ph}₂ (PPh₃)₄](PF₆) ₂ shows the presence of short Pt•••O contacts. In contrast, the corresponding chloro compounds [typified by PhC(O)CH₂Cl] and imino analogues [e.g. PhC(NOH)CH₂Br] do not dialkylate [Pt₂ (μ-S)₂(PPh₃)₄]. The ability of PhC(O)CH₂Br to dialkylate [Pt₂(μ-S)₂(PPh₃)₄] allows the synthesis of new mixed-alkyl dithiolate derivatives of the type [Pt₂{μ-SCH₂C(O)Ph}(μ-SR)(PPh₃)₄]²⁺ (R = Et or n-Bu), through alkylation of in situ-generated monoalkylated compounds [Pt₂(μ-S)(μ-SR)(PPh₃)₄]⁺ (from [Pt₂(μ-S)₂(PPh₃)₄] and excess RBr). In these heterodialkylated systems ligand replacement of PPh₃ occurs by the bromide ions in the reaction mixture forming monocations [Pt₂{μ-SCH₂C(O)Ph}(μ-SR)(PPh₃)₃Br]⁺. This ligand substitution can be easily suppressed by addition of PPh₃ to the reaction mixture. The complex [Pt₂{μ-SCH₂C(O)Ph}(μ-SBu)(PPh₃)₄]²⁺ was crystallographically characterised. X-ray crystal structures of the bromide-containing complexes [Pt₂{μ-SCH₂C(O)Ph}(μ-SR)(PPh₃)₃Br]+ (R = Et, Bu) are also reported. In both structures the coordinated bromide is trans to the SCH₂C(O)Ph ligand, which adopts an axial position, while the ethyl and butyl substituents adopt equatorial positions, in contrast to the structures of the dialkylated complexes [Pt₂{μ-SCH₂C(O)Ph}₂(PPh₃)₄]²⁺ and [Pt₂{μ-SCH₂C(O)Ph}(μ-SBu)(PPh₃)₄]²⁺ (and many other known analogues) where both alkyl groups adopt axial positions.

text: Further studies on the dialkylation chemistry of [Pt₂(μ-S)₂(PPh₃)₄] with activated alkyl halides RC(O)CH₂X (X = Cl, Br) Further studies have been carried out into the reactivity of [Pt₂(μ-S)₂(PPh₃)₄] towards a range of activated alkylating agents of the type RC(O)CH₂X (R = organic moiety e.g. phenyl, pyrenyl; X = Cl, Br). Alkylation of both sulfide centres is observed for PhC(O)CH₂Br, 3-(bromoacetyl)coumarin [CouC(O)CH₂Br], and 1-(bromoacetyl)pyrene [PyrC(O)CH2Br], giving dications [Pt₂{μ-SCH₂C(O)R}₂ (PPh₃)₄] ²⁺, isolated as their PF₆⁻ salts. The X-ray structure of [Pt₂{μ-SCH₂C(O)Ph}₂ (PPh₃)₄](PF₆) ₂ shows the presence of short Pt•••O contacts. In contrast, the corresponding chloro compounds [typified by PhC(O)CH₂Cl] and imino analogues [e.g. PhC(NOH)CH₂Br] do not dialkylate [Pt₂ (μ-S)₂(PPh₃)₄]. The ability of PhC(O)CH₂Br to dialkylate [Pt₂(μ-S)₂(PPh₃)₄] allows the synthesis of new mixed-alkyl dithiolate derivatives of the type [Pt₂{μ-SCH₂C(O)Ph}(μ-SR)(PPh₃)₄]²⁺ (R = Et or n-Bu), through alkylation of in situ-generated monoalkylated compounds [Pt₂(μ-S)(μ-SR)(PPh₃)₄]⁺ (from [Pt₂(μ-S)₂(PPh₃)₄] and excess RBr). In these heterodialkylated systems ligand replacement of PPh₃ occurs by the bromide ions in the reaction mixture forming monocations [Pt₂{μ-SCH₂C(O)Ph}(μ-SR)(PPh₃)₃Br]⁺. This ligand substitution can be easily suppressed by addition of PPh₃ to the reaction mixture. The complex [Pt₂{μ-SCH₂C(O)Ph}(μ-SBu)(PPh₃)₄]²⁺ was crystallographically characterised. X-ray crystal structures of the bromide-containing complexes [Pt₂{μ-SCH₂C(O)Ph}(μ-SR)(PPh₃)₃Br]+ (R = Et, Bu) are also reported. In both structures the coordinated bromide is trans to the SCH₂C(O)Ph ligand, which adopts an axial position, while the ethyl and butyl substituents adopt equatorial positions, in contrast to the structures of the dialkylated complexes [Pt₂{μ-SCH₂C(O)Ph}₂(PPh₃)₄]²⁺ and [Pt₂{μ-SCH₂C(O)Ph}(μ-SBu)(PPh₃)₄]²⁺ (and many other known analogues) where both alkyl groups adopt axial positions.

year: 2011

title: The effects of post-operative antibiotics in endoscopic sinus surgery

authors: Challis, Jacinda

subjects: Chronic rhinosinusitis

abstract: Previous research into post-operative antibiotic usage for chronic rhinosinusitis (CRS) patients generated contradictory results. Some studies found that post-operative antibiotics did not improve the short-term clinical outcomes (Jiang et al., 2008; Lehmann et al., 2020; Liang et al., 2011) while some did (Albu & Lucaciu, 2010). Those studies had also focused primarily on the clinical outcomes of the surgery, overlooking the potential impact of prophylactic antibiotics on the sinonasal microbiome. Using cultivation-independent methods, this study aimed to examine the impact of post-operative antibiotics on the sinonasal microbiome alongside short-term clinical outcomes of CRS patients undergoing endoscopic sinus surgery (ESS). Twelve patients undergoing ESS to treat their CRS were enrolled in this study and randomly distributed into two groups: an antibiotic treatment group and a placebo treatment group. The antibiotic treatment group received doxycycline for 28 days after surgery. Clinical information, including computed tomography scan, symptom questionnaires, and nasal endoscopy, were collected for each patient before and after ESS. Swab and tissue samples were collected and underwent DNA extraction, PCR amplification of the bacterial 16S rRNA gene, and amplicon sequencing analysis to longitudinally characterise each patient’s sinonasal microbiome. There were no differences in symptom scores or endoscopic/radiological scores between treatment groups before or after the surgery, and there was no significant difference in the microbiome between the treatment groups after surgery. Our preliminary study showed that post-operative antibiotics did not improve short-term clinical outcomes for CRS patients undergoing ESS, and there was no significant difference in the microbiome between treatments, either. However, our preliminary findings reflect only short-term effects, and many of our analyses were statistically underpowered due to the modest sample size. A larger study is needed to explore specific patterns observed in our data with greater confidence.

text: The effects of post-operative antibiotics in endoscopic sinus surgery Previous research into post-operative antibiotic usage for chronic rhinosinusitis (CRS) patients generated contradictory results. Some studies found that post-operative antibiotics did not improve the short-term clinical outcomes (Jiang et al., 2008; Lehmann et al., 2020; Liang et al., 2011) while some did (Albu & Lucaciu, 2010). Those studies had also focused primarily on the clinical outcomes of the surgery, overlooking the potential impact of prophylactic antibiotics on the sinonasal microbiome. Using cultivation-independent methods, this study aimed to examine the impact of post-operative antibiotics on the sinonasal microbiome alongside short-term clinical outcomes of CRS patients undergoing endoscopic sinus surgery (ESS). Twelve patients undergoing ESS to treat their CRS were enrolled in this study and randomly distributed into two groups: an antibiotic treatment group and a placebo treatment group. The antibiotic treatment group received doxycycline for 28 days after surgery. Clinical information, including computed tomography scan, symptom questionnaires, and nasal endoscopy, were collected for each patient before and after ESS. Swab and tissue samples were collected and underwent DNA extraction, PCR amplification of the bacterial 16S rRNA gene, and amplicon sequencing analysis to longitudinally characterise each patient’s sinonasal microbiome. There were no differences in symptom scores or endoscopic/radiological scores between treatment groups before or after the surgery, and there was no significant difference in the microbiome between the treatment groups after surgery. Our preliminary study showed that post-operative antibiotics did not improve short-term clinical outcomes for CRS patients undergoing ESS, and there was no significant difference in the microbiome between treatments, either. However, our preliminary findings reflect only short-term effects, and many of our analyses were statistically underpowered due to the modest sample size. A larger study is needed to explore specific patterns observed in our data with greater confidence.

year: 2021

title: How do colorectal cancer patients rate their GP: a mixed methods study

authors: Blackmore, Tania Louise

subjects: Science & Technology

abstract: Background: New Zealand (NZ) has a high incidence of colorectal cancer (CRC) and low rates of early diagnosis. With screening not yet nationwide, the majority of CRC is diagnosed through general practice. A good patient-general practitioner (GP) relationship can facilitate prompt diagnosis, but when there is a breakdown in this relationship, delays can occur. Delayed diagnosis of CRC in NZ receives a disproportionally high number of complaints directed against GPs, suggesting deficits in the patient-GP connection. We aimed to investigate patient-reported confidence and ratings of their GP following the diagnostic process. 
Methods: This study is a mixed methods analysis of responses to a structured questionnaire and free text comments from patients newly diagnosed with CRC in the Midland region of NZ. A total of 195 patients responded to the structured questionnaire, and 113 patients provided additional free text comments. Descriptive statistics were used to describe the study population and chi square analysis determined the statistical significance of factors possibly linked to delay. Free text comments were analysed using a thematic framework. 
Results: Most participants rated their GP as ‘Very good/Good’ at communication with patients about their health conditions and involving them in decisions about their care, and 6.7% of participants rated their overall level of confidence and trust in their GP as ‘Not at all’. Age, gender, ethnicity and a longer diagnostic interval were associated with lower confidence and trust. Free text comments were grouped in to three themes: 1. GP Interpersonal skills; (communication, listening, taking patient symptoms seriously), 2. Technical competence; (speed of referral, misdiagnoses, lack of physical examination), and 3. Organisation of general practice care; (appointment length, getting an appointment, continuity of care). 
Conclusions: Māori, females, and younger participants were more likely to report low confidence and trust in their GP. Participants associate a poor diagnostic experience with deficits in the interpersonal and technical skills of their GP, and health system factors within general practice. Short appointment times, access to appointments and poor GP continuity are important components of how patients assess their experience and are particularly important to ensure equal access for Māori patients.

text: How do colorectal cancer patients rate their GP: a mixed methods study Background: New Zealand (NZ) has a high incidence of colorectal cancer (CRC) and low rates of early diagnosis. With screening not yet nationwide, the majority of CRC is diagnosed through general practice. A good patient-general practitioner (GP) relationship can facilitate prompt diagnosis, but when there is a breakdown in this relationship, delays can occur. Delayed diagnosis of CRC in NZ receives a disproportionally high number of complaints directed against GPs, suggesting deficits in the patient-GP connection. We aimed to investigate patient-reported confidence and ratings of their GP following the diagnostic process. 
Methods: This study is a mixed methods analysis of responses to a structured questionnaire and free text comments from patients newly diagnosed with CRC in the Midland region of NZ. A total of 195 patients responded to the structured questionnaire, and 113 patients provided additional free text comments. Descriptive statistics were used to describe the study population and chi square analysis determined the statistical significance of factors possibly linked to delay. Free text comments were analysed using a thematic framework. 
Results: Most participants rated their GP as ‘Very good/Good’ at communication with patients about their health conditions and involving them in decisions about their care, and 6.7% of participants rated their overall level of confidence and trust in their GP as ‘Not at all’. Age, gender, ethnicity and a longer diagnostic interval were associated with lower confidence and trust. Free text comments were grouped in to three themes: 1. GP Interpersonal skills; (communication, listening, taking patient symptoms seriously), 2. Technical competence; (speed of referral, misdiagnoses, lack of physical examination), and 3. Organisation of general practice care; (appointment length, getting an appointment, continuity of care). 
Conclusions: Māori, females, and younger participants were more likely to report low confidence and trust in their GP. Participants associate a poor diagnostic experience with deficits in the interpersonal and technical skills of their GP, and health system factors within general practice. Short appointment times, access to appointments and poor GP continuity are important components of how patients assess their experience and are particularly important to ensure equal access for Māori patients.

year: 2021-04-08