Increased risk of non-fatal overdose associated with non-prescribed benzodiazepine use in Scotland, UK.

BACKGROUND: Drug-related deaths (DRDs) in Scotland increased for seven years in a row between 2014 and 2020, consolidating Scotland's place at the top of the United Kingdom and European drug-related mortality charts. One of the defining features of this recent and rapid rise has been the role of benzodiazepines, which are now involved in the majority of all DRDs. These deaths are linked to use of non-prescribed, benzodiazepine-type novel psychoactive substances (NPS) which have been identified by the United Nations as a global threat to public health. This study aimed to estimate the prevalence and determinants of non-prescribed benzodiazepine use and its association with recent non-fatal overdose among a national sample of people who inject drugs (PWID). METHODS: Data from the 2019-20 Needle Exchange Surveillance Initiative (NESI) was analysed using logistic regression. NESI is a voluntary, anonymous, biennial, cross-sectional, bio-behavioural survey of PWID attending community-based services providing injecting equipment in mainland Scotland. RESULTS: Prevalence of non-prescribed benzodiazepine use in the past six months was 52% and significantly associated with age (aOR 0.97, 0.96-0.98), frequent incarceration (aOR 1.29, 1.07-1.57), recent public injecting (aOR 3.25, 2.33-4.55), a recent methadone prescription (aOR 1.87, 1.51-2.33), and a history of benzodiazepine prescription (aOR 1.92, 1.47-2.52). In addition, non-prescribed benzodiazepine use was significantly associated with non-fatal overdose in the past year among PWID (aOR 2.47, 1.90-3.21). CONCLUSION: This study found a high prevalence of non-prescribed benzodiazepine use among a national sample of PWID in Scotland. Prevalence was highest among populations known to be at increased risk of drug-related death and use was strongly associated with overdose. These novel findings highlight the scale of the non-prescribed benzodiazepine issue Scotland faces, and the urgency required to expand its harm reduction infrastructure to address this unique element of its overdose crisis.

National increase in the community supply of take-home naloxone associated with a mass media campaign in Scotland: a segmented time series analysis.

BACKGROUND: Take-home naloxone (THN) programmes have been associated with reductions in opioid-related mortality. In response to high rates of drug-related deaths in Scotland, the Scottish Government commissioned the 'How to save a life' (HTSAL) mass media campaign to: (1) increase awareness of drug-related deaths and how to respond to an overdose, and (2) increase the supply of THN. The aim of this study was to assess the effect of the campaign on the supply of THN. METHODS: We used an interrupted time series design to assess the effect of the HTSAL mass media campaign on the national community supply of THN. The study time period was August 2020-December 2021. We modelled two key dates: the start of the campaign (week beginning (w/b) 30th of August 2021) and after the end of the main campaign (w/b 25th of October 2021). RESULTS: The total number of THN kits distributed in the community in Scotland during the study period was 27,064. The mean number of THN kits distributed per week (relative to the pre-campaign period), increased by 126% during the campaign and 57% post-campaign. In segmented regression analyses, the pre-campaign trend in the number of THN kits supplied was increasing by an average of 1% each week (RR=1.01, 95% CI 1.01 to 1.01, p<0.001). Once the campaign started, a significant change in level was observed, and the number of kits increased by 75% (RR=1.75, 95% CI 1.29 to 2.40, p<0.001). The trend during the campaign was stable (i.e. not increasing or decreasing) but a significant change in level was observed when the campaign ended, and the number of THN kits supplied decreased by 32% (RR=0.68, 95% CI 0.46 to 0.98, p = 0.042). The trend during the post-campaign period was stable. CONCLUSIONS: The HTSAL campaign had a short term, but large and significant impact, on the community supply of THN in Scotland. Mass media campaigns could be combined with other interventions and strategies to maintain the increased uptake of THN outside of campaign periods.

How to save a life: Public awareness of a national mass media take home naloxone campaign, and effects of exposure to campaign components on overdose knowledge and responses.

BACKGROUND: Take home naloxone (THN) programmes are effective at reducing opioid related mortality, but require high levels of distribution, including to the general public. Mass media campaigns can be effective in improving public understanding of a topic and encouraging behavior change. Whilst mass media campaigns focusing on naloxone have been developed internationally, there is a lack of research on their potential impact. We investigated the effects of components of a recent national mass media campaign (Scotland, UK) designed to improve public awareness of drug related deaths, and readiness to intervene. METHODS: We undertook a cross-sectional online experimental study with a randomized design, conducted with a nationally representative sample. Participants (N = 1551; 52.6% female; age 46.1±16.5 years) were assessed on overdose knowledge and readiness to intervene after presentation of eight combinations of campaign components. RESULTS: Compared to a basic campaign description, exposure to all types of campaign component were associated with higher overdose knowledge (p < .001), but not knowledge of what to do in response to an overdose (p = .374), or readiness to intervene (p= .286). The greatest effects were associated with a media rich audio-visual resource (animated video with a popular song on the soundtrack, and narrated by a well-known actor). CONCLUSION: Our data suggest that harm reduction is an appropriate topic for large-scale mass media campaigns. However, effects may be limited to knowledge and awareness raising in the general public, and may be related to the types of media used. Audience segmentation is important and more general messaging about drug related deaths may be more appropriate for the majority of audiences.

Impact of COVID-19 & Response Measures on HIV-HCV Prevention Services and Social Determinants in People Who Inject Drugs in 13 Sites with Recent HIV Outbreaks in Europe, North America and Israel.

HIV/HCV prevention among people who inject drugs (PWID) is of key public health importance. We aimed to assess the impact of COVID-19 and associated response measures on HIV/HCV prevention services and socio-economic status of PWID in high-HIV-risk sites. Sites with recent (2011-2019) HIV outbreaks among PWID in Europe North America and Israel, that had been previously identified, were contacted early May 2020. Out of 17 sites invited to participate, 13 accepted. Semi-structured qualitative site reports were prepared covering data from March to May 2020, analyzed/coded and confirmed with a structured questionnaire, in which all sites explicitly responded to all 103 issues reported in the qualitative reports. Opioid maintenance treatment, needle/syringe programs and antiretroviral treatment /hepatitis C treatment continued, but with important reductions and operational changes. Increases in overdoses, widespread difficulties with food and hygiene needs, disruptions in drug supply, and increased homelessness were reported. Service programs rapidly reformed long established, and politically entrenched, restrictive service delivery policies. Future epidemic control measures should include mitigation of negative side-effects on service provision and socio-economic determinants in PWID.

RESUMEN: La prevención del VIH/VHC entre las personas que se inyectan drogas (PWID) es de vital importancia para la salud pública. Nuestro objetivo fue evaluar el impacto de COVID-19 y las medidas de respuesta asociadas en los servicios de prevención del VIH/VHC y el estado socioeconómico de las PWID en sitios de alto riesgo de VIH. Se contactó con sitios con brotes recientes (2011­2019) de VIH entre PWID en Europa, América del Norte e Israel, que habían sido previamente identificados, a principios de mayo de 2020. De los 17 sitios invitados a participar, 13 aceptaron. Se prepararon informes cualitativos semiestructurados del sitio que cubrían los datos de marzo a mayo de 2020, analizados/codificados y confirmados con un cuestionario estructurado, en el que todos los sitios respondieron explícitamente a los 103 asuntos reportados en los informes cualitativos. El tratamiento de mantenimiento con opiáceos, los programas de agujas/jeringas y el tratamiento antirretroviral/tratamiento de la hepatitis C continuaron, pero con importantes reducciones y cambios operativos. Se reportaron aumentos en las sobredosis, dificultades generalizadas con las necesidades alimentarias y de higiene, interrupciones en el suministro de medicamentos y aumento de personas sin hogar. Los programas de servicios reformaron rápidamente las políticas restrictivas de prestación de servicios, establecidas desde hace mucho tiempo y políticamente arraigadas. Las futuras medidas de control de epidemias deben incluir la mitigación de los efectos secundarios negativos en la prestación de servicios y los determinantes socioeconómicos en las PWID.

From the clinic to the street: the changing role of benzodiazepines in the Scottish overdose epidemic.

Drug-related deaths in Scotland increased for seven years in a row between 2014 and 2020 consolidating Scotland's place at the top of the United Kingdom and European drug-related mortality charts. One of the defining features of this recent and rapid rise has been the role of benzodiazepines which are now involved in two-thirds of all cases. Policy decisions over four decades have contributed to the supply and demand drivers of this unique element of the Scottish overdose crisis. An illicit market once populated by diverted prescription medications is now dominated by a toxic supply of NPS-type benzodiazepines or so-called 'street benzos' which have increased the risk environment for people who use drugs. In response, Scotland needs to urgently expand its harm reduction infrastructure and implement safer supply, drug testing and drug consumption rooms. Such a response should be made in parallel to addressing the socioeconomic inequalities which are fuelling an epidemic of global significance.

National population prevalence of antibodies to SARS-CoV-2 among pregnant women in Scotland during the second wave of the COVID-19 pandemic: a prospective national serosurvey.

OBJECTIVES: This study aimed to determine SARS-CoV-2 seroprevalence among pregnant women in the Scottish population during the second wave of the COVID-19 pandemic. STUDY DESIGN: Prospective national serosurvey. METHODS: We tested 13,428 residual samples retrieved from pregnant women participating in the first trimester combined ultrasound and biochemical screening for fetal trisomy across Scotland for SARS-CoV-2 antibodies over a 6-month period from November 2020 to April 2021. Seroprevalence estimates were adjusted for the sensitivity and specificity of the assays and weighted to reference populations. RESULTS: Seroprevalence rates in the antenatal samples significantly increased from 5.5% (95% confidence interval [CI] 4.7%-6.5%) in the 5-week period up to and including International Organization for Standardization (ISO) Week 51 (w/b Monday 14 December 2020) to 11.3% (95% CI 10.1%-12.6%) in the 5-week period up to and including ISO Week 14 (w/b Monday 5 April 2021). Increasing seroprevalence trends across the second wave were observed among all age groups. CONCLUSIONS: By the end of the second wave of the COVID-19 pandemic, approximately one in 10 women tested around the end of the first trimester of pregnancy had antibodies to SARS-CoV-2, suggesting that the vast majority were still susceptible to COVID-19 as they progressed to the later stages of pregnancy, when risks from infection are elevated for both mother and baby.

National population prevalence of antibodies to SARS-CoV-2 in Scotland during the first and second waves of the COVID-19 pandemic.

OBJECTIVES: Studies that measure the prevalence of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ('seroprevalence') are essential to understand population exposure to SARS-CoV-2 among symptomatic and asymptomatic individuals. We aimed to measure seroprevalence in the Scottish population over the course of the COVID-19 pandemic - from before the first recorded case in Scotland through to the second pandemic wave. STUDY DESIGN: The study design of this study is serial cross sectional. METHODS: We tested 41,477 residual samples retrieved from primary and antenatal care settings across Scotland for SARS-CoV-2 antibodies over a 12-month period from December 2019-December 2020 (before rollout of COVID-19 vaccination). Five-weekly rolling seroprevalence estimates were adjusted for the sensitivity and specificity of the assays and weighted to reference populations. Temporal trends in seroprevalence estimates and weekly SARS-CoV-2 notifications were compared. RESULTS: Five-weekly rolling seroprevalence rates were 0% until the end of March, when they increased contemporaneously with the first pandemic wave. Seroprevalence rates remained stable through the summer (range: 3%-5%) during a period of social restrictions, after which they increased concurrently with the second wave, reaching 9.6% (95% confidence interval [CI]: 8.4%-10.8%) in the week beginning 28th December in 2020. Seroprevalence rates were lower in rural vs. urban areas (adjusted odds ratio [AOR]: 0.70, 95% CI: 0.61-0.79) and among individuals aged 20-39 years and 60 years and older (AOR: 0.74, 95% CI: 0.64-0.86; AOR: 0.80, 95% CI: 0.69-0.91, respectively) relative to those aged 0-19 years. CONCLUSIONS: After two waves of the COVID-19 pandemic, less than one in ten individuals in the Scottish population had antibodies to SARS-CoV-2. Seroprevalence may underestimate the true population exposure as a result of waning antibodies among individuals who were infected early in the first wave.

Increasing drug-related mortality rates over the last decade in Scotland are not just due to an ageing cohort: A retrospective longitudinal cohort study.

BACKGROUND: In Europe, North America, and Australia, mortality due to drug-related (DR) causes amongst people who inject drugs (PWID) is a major issue. Our objective was to characterise temporal trends in DR mortality rates in a large cohort of PWID in Scotland over the past decade, all of whom had been diagnosed with hepatitis C virus (HCV) infection, and to investigate factors associated with DR mortality. METHODS: Retrospective longitudinal cohort study linking Scotland's national HCV Diagnosis Database and deaths registry. The study cohort consisted of all individuals with likely injection drug use-related route of HCV acquisition, who had been diagnosed with HCV between 1991 and 2018, and were alive and aged under 65 years on 1 January 2009. We used Lexis expansion to adjust for ageing cohort effects and calculated the mortality rate from an underlying/contributing DR cause over the period 2009-2018. We fitted Poisson regression models to estimate the temporal trend adjusting for attained age, sex, referral setting, region, and viraemic status at baseline. RESULTS: Amongst the study population (n = 35,065; 236,914 person-years), a total of 1900 DR deaths occurred; the DR mortality rate increased from 5.6/1000 [101 deaths] in 2009 to 12.4/1000 [342] person-years in 2018. Increasing trends were observed for all age-groups except 55-64 years. The overall DR mortality rate was highest for referrals for HCV testing from prison (11.0/1000) and hospital settings (10.0/1000). Mortality increased with calendar time period, with significantly raised adjusted rate ratios (RRs) from 2015 (RR=1.40, 95% CI:1.16-1.69) to 2018 (RR=2.23, 95% CI:1.88-2.64), compared with 2011-2012, for older age (35-44: RR=1.37, 95% CI:1.20-1.56; 45-54: RR=1.32, CI:1.14-1.53) compared with <35 years, for persons diagnosed with HCV since 2009 (RR=1.34, 95% CI:1.21-1.49), and for prison and hospital referrals (RRs of 1.30, 1.37) compared with GP referrals. CONCLUSION: Increasing DR mortality rates in Scotland over the past decade are not just due to an ageing cohort. Harm reduction services will likely need to expand and adapt to reverse the recent upward trends in DR mortality in PWID.

Enhanced surveillance of COVID-19 in Scotland: population-based seroprevalence surveillance for SARS-CoV-2 during the first wave of the epidemic.

OBJECTIVES: The impact of the COVID-19 pandemic in Scotland has been amongst the most severe in Europe. Serological surveillance is critical to determine the overall extent of infection across populations and to inform the public health response. This study aimed to estimate the proportion of people who have antibodies to SARS-CoV-2 ('seroprevalence') in the general population of Scotland and to see if this changes over time. STUDY DESIGN/METHODS: Between International Organization for Standardization (ISO) week 17 (i.e. week commencing 20th April) and ISO week 25 (week commencing 15 June), 4751 residual blood samples were obtained from regional biochemistry laboratories in six participating regional health authority areas covering approximately 75% of the Scottish population. Samples were tested for the presence of anti-SARS-CoV-2 IgG antibodies using the LIAISON®SARS-CoV-2 S1/S2 IgG assay (DiaSorin, Italy). Seroprevalence rates were adjusted for the sensitivity and specificity of the assay using Bayesian methods. RESULTS: The combined adjusted seroprevalence across the study period was 4.3% (95% confidence interval: 4.2%-4.5%). The proportion varied each week between 1.9% and 6.8% with no difference in antibody positivity by age, sex or geographical area. CONCLUSIONS: At the end of the first wave of the COVID-19 pandemic, only a small fraction of the Scottish population had antibodies to SARS-CoV-2. Control of COVID-19 requires the ability to detect asymptomatic and mild infections that would otherwise remain undetected through existing surveillance systems. This is important to determine the true number of infections within the general population which, in turn, can help to understand transmission, inform control measures and provide a denominator for the estimation of severity measures such as the proportion of infected people who have been hospitalised and/or have died.

Increased case-finding and uptake of direct-acting antiviral treatment essential for micro-elimination of hepatitis C among people living with HIV: a national record linkage study.

OBJECTIVES: Micro-elimination of hepatitis C virus (HCV) in people living with HIV (PLHIV) and co-infected with HCV has been proposed as a key contribution to the overall goal of HCV elimination. While other studies have examined micro-elimination in HIV-treated cohorts, few have considered HCV micro-elimination among those not treated for HIV or at a national level. METHODS: Through data linkage of national and sentinel surveillance data, we examined the extent of HCV testing, diagnosis and treatment among a cohort of PLHIV in Scotland identified through the national database of HIV-diagnosed individuals, up to the end of 2017. RESULTS: Of 5018 PLHIV, an estimated 797 (15%) had never been tested for HCV and 70 (9%) of these had undiagnosed chronic HCV. The odds of never having been tested for HCV were the highest in those not on HIV treatment [adjusted odds ratio (aOR) = 7.21, 95% confidence interval (CI): 5.15-10.10). Overall HCV antibody positivity was 11%, and it was at its highest among people who inject drugs (49%). Most of those with chronic HCV (91%) had attended an HCV treatment clinic but only half had been successfully treated (54% for those on HIV treatment, 12% for those not) by the end of 2017. The odds of never having been treated for HCV were the highest in those not on HIV treatment (aOR = 3.60, 95% CI: 1.59-8.15). CONCLUSIONS: Our data demonstrate that micro-elimination of HCV in PLHIV is achievable but progress will require increased effort to engage and treat those co-infected, including those not being treated for their HIV.

Effects of messaging on public support for drug consumption rooms in scotland, UK.

BACKGROUND: There is evidence to suggest that medically supervised drug consumption rooms (DCRs) may form part of responses to reduce drug-related harm. Although DCRs have been established globally, they are perceived by some to be a controversial approach in the UK, and Government has repeatedly rejected proposals to establish one in Glasgow, Scotland. As public support is an important component of policy development and enactment, we sought to investigate the effects of different types of message framing on public support for DCR. METHODS: We undertook a cross-sectional online study with a randomised design, conducted with a nationally representative sample. Participants were randomised to one of six message conditions comprising combinations of four components. All conditions included i) a basic description of a DCR, and conditions included combinations of ii) factual information; iii) pre-emptive refutation of common public concerns about DCR; and/or iv) a sympathetic narrative describing a mother whose son died from a heroin overdose. After reading each message, participants completed a bespoke measure assessing support for DCR. Data were analysed using ANCOVA. RESULTS: Complete data were obtained from 1591 participants (50.3% Female; mean age 44.9 ± 16.1 years). Compared to reading a basic description of DCR alone, there was greater support for DCR in participants receiving the refutation (p < .001); sympathetic + factual (p < .05); and sympathetic + factual + refutation (p < .001) message conditions. Presenting factual or sympathetic messages alone were not associated with increased support. CONCLUSION: Our findings suggest that public support for DCRs is not improved through communication of factual statements outlining potential benefits of the intervention alone. Advocates seeking to foster public support, and thus influence policy making, should also consider communication campaigns that address common concerns that the public might have about DCRs, and present the intervention in relation to potential benefits that they hold for people indirectly affected by drug-related harm.

'We are still obsessed by this idea of abstinence': A critical analysis of UK news media representations of proposals to introduce drug consumption rooms in Glasgow, UK.

BACKGROUND: Drug consumptions rooms (DCRs) are a well-established and evidence-based harm reduction response to drug use. Recently, a consortium led by health services in Glasgow, United Kingdom (UK), proposed piloting a DCR. In this article, we examine how the proposals were represented in news media reporting, and the possible effects of such reporting. METHODS: A quantitative content and qualitative thematic analysis of UK news media (n = 174 articles) representations of the proposals to introduce DCRs in the city of Glasgow, UK, was conducted. Analysis was informed by Bacchi's (2009, 2012, 2017) approach to policy analysis, 'What's the problem represented to be?' FINDINGS: Competing representations of the 'problem' of injecting drug use (IDU) were contested by a range of actors with different political visions. The applicability of the 'evidence base', potential benefits of DCRs to both users and the public, and the associated economic costs, were presented in differing ways depending on the underlying assumptions and presumptions of the arguments constructed (e.g. harm reduction vs recovery). As a result, a number of conflicting subject positions were presented that may have implications for the way that people who inject drugs (PWID) see themselves, and how they are viewed and treated by society. Whilst proponents positioned DCRs within a discourse of public health, an underlying rhetoric of abstinence and recovery underpinned the arguments against DCRs. It was this latter discourse that underpinned the UK Government's rejection of the proposals, which the Scottish Government were prevented from overruling within the political constraints of their devolved powers, with the lived effect of people who use drugs (PWUD) being denied access to public health services that mitigate harm. CONCLUSION: We conclude that attempts to introduce and gain public and political support for harm reduction responses such as DCRs through the news media face challenges within the historical and political context of prohibitionist UK drugs policy.

Influence of sorbitol on protein crowding in solution and freeze-concentrated phases.

Small-angle neutron scattering was employed to study protein crowding under freezing conditions that mimic those used in pharmaceutical processing. The results demonstrate that, although there is an increase in heterogeneity as the temperature is reduced, sorbitol reduces protein crowding in both solution and freeze-concentrated phases, thus protecting the protein from forming oligomers or irreversible aggregates.

Delivering alcohol screening and alcohol brief interventions within general dental practice: rationale and overview of the evidence.

Alcohol consumption and affordability in the UK has increased over the last 50 years and is associated with a range of adverse oral health outcomes, the most serious of which, oral cancer, is also increasing in incidence. Despite this, routine screening and intervention relating to alcohol consumption within general dental practice remains uncommon. This review of the literature describes the background and outlines the evidence base for undertaking alcohol screening and delivering brief interventions in general dental practice. Consideration will be given to the rationale for, and range of issues related to, introducing this into general dental practice.

Effect of manufacturing process parameters on virus inactivation by dry heat treatment at 80 degrees C in factor VIII.

BACKGROUND AND OBJECTIVES: Dry heat treatment at 80 degrees C for 72 h is used as a virus inactivation step for some coagulation factor concentrates such as Bio Products Laboratory's (BPL) factor VIII 8Y. In the current study, the effect of this process has been tested on a range of viruses. In addition the effect of various manufacturing process parameters on virus inactivation has been investigated. MATERIALS AND METHODS: Samples of product intermediate were obtained from manufacturing, spiked with virus and subjected to freeze drying and dry heat treatment. Virus inactivation was determined by infectivity assay. RESULTS: Freeze drying followed by dry heat treatment was effective for inactivating a wide range of enveloped and nonenveloped viruses. Sucrose or protein concentration had no effect on virus inactivation. Product presentation or the interruption of heat treatment also had no effect. The inactivation of some of the viruses was greater at higher residual water content but under such conditions the stability of the product was reduced. CONCLUSION: This virus inactivation step was effective for a wide range of viruses and over the range of process conditions encountered in manufacturing. This demonstrates the robustness of this process step.

Synthesis of 14-oxa-1,4,8,11-tetraazabicyclo[9.5.3]nonadecane(L1) and a spectroscopic and structural study of [Ni(L1)(ClO4)](ClO4) and of the macrobicyclic precursor diamide complex, [Ni(HL2)](ClO4); chloride substitution kinetics of the corresponding [Ni(III)(L1)]3+ species.

The pentadentate ligand 14-oxa-1,4,8,11-tetraazabicyclo[9.5.3]nonadecane (L1) has been synthesized by the high dilution cyclization of 1-oxa-4,8-diazacyclododecane ([10]aneN(2)O) (1) with 1,3-bis(alpha-chloroacetamido)propane (2) and subsequent reduction of the diamide intermediate. The structure [Ni(L1)(ClO(4))](ClO(4)) (P2(1)/c (no. 14), a = 8.608(3), b = 16.618(3), c = 14.924(4) A, beta = 91.53(3) degrees converged at R = 0.050 (R(w) = 0.046) for 307 parameters using 2702 reflections with I > 2sigma(I). For the nickel(II) complex of the (monodeprotonated) precursor diamide ligand 14-oxa-1,4,8,11-tetraazabicyclo[9.5.3]nonadecane-3,9-dione (H(2)L2), [Ni(HL2)](ClO(4)) (Pbca (no. 61), a = 15.1590(3), b = 13.235(2), c = 18.0195(6) A), the structure converged at R = 0.045 (R(w) = 0.038) for 265 parameters using 1703 reflections with I > 3sigma(I). In the reduced system, the cyclam-based ligand adopts a trans-III configuration. The [Ni(L1)(ClO(4))](2+) ion is pseudooctahedral with the Ni-O(ether) 2.094(3) A distance shorter than the Ni-O(perchlorate) 2.252(4) A. The nickel(II) and nickel(III) complexes are six-coordinate in solution. Oxidation of [Ni(L1)(OH(2))](2+) with K(2)S(2)O(8) in aqueous media yielded an axial d(7) Ni(III) species (g( perpendicular) = 2.159 and g( perpendicular) = 2.024 at 77 K). The [Ni(L1)(solv)](2+) ion in CH(3)CN showed two redox waves, Ni(II/I) (an irreversible cathodic peak, E(p,c) = -1.53 V) and Ni(III/II) (E(1/2) = 0.85 V (reversible)) vs Ag/Ag(+). The complex [Ni(HL2)](ClO(4)) displays square-planar geometry with monodeprotonation of the ligand. The ether oxygen is not coordinated. Ni-O(3) = 2.651(6) A and Ni-O(3a) = 2.451(12) A, respectively. The Ni(III/II) oxidation at E(1/2) = 0.24 V (quasi-reversible) vs Ag/Ag(+) is considerably lower than the saturated system. The kinetics of Cl(-) substitution at [Ni(L1)(solv)](3+) are pH dependent. Detachment of the ether oxygen atom is proposed, with insertion of a protonated water molecule which deprotonates at a pK(a) more acidic than in the corresponding cyclam complex. Mechanistic implications are discussed.

Quenching of Triplet State Tetrakis(&mgr;-pyrophosphito-PP')diplatinate(II) by Nickel(II) Macrocyclic and Tris-diimine Complexes.

The excited state of tetrakis(&mgr;-pyrophosphito-PP')diplatinate(II), Pt(2)(pop)(4)(4)(-), has been shown to be reductively quenched by a series of Ni(II) complexes. Steady-state photolysis of Pt(2)(pop)(4)(4)(-) in the presence of Ni(cyclam)(2+) and SO(4)(2)(-) ions was followed by absorption spectroscopy and showed the production of the Ni(III) complex with low efficiency. The Ni(III) yield was enhanced in the presence of oxygen presumably because of scavenging of Pt(2)(pop)(4)(5)(-) from the solvent-caged {Pt(2)(II,I).Ni(III)} primary product pair resulting from electron transfer. Cage escape yields of 0.028 in N(2) saturated solution and 0.054 in aerated solutions were estimated from the data. For a series of complexes with decreasing redox potential, the rate constants for their (3)Pt(2)(pop)(4)(4)(-) phosphorescence lifetime quenching decreased with driving force DeltaG, consistent with Rehm-Weller behavior and leading to a reorganization energy of approximately 60 kJ mol(-)(1). The diffusional rate constant calculated from the Debye-Smoluchowski equation was 1.6 x 10(10) M(-)(1) s(-)(1), in excellent agreement with the observed value of 1.6 x 10(10) M(-)(1) s(-)(1) based on the Rehm-Weller equation. The transmission factor for the electron transfer was estimated at 10(-)(4), in the weakly adiabatic region. Although the Rehm-Weller treatment has been used successfully in reactions involving mainly uncharged organic reactants, in this investigation it leads to an unrealistic ratio for the rate constants for the diffusive separation of the charged reactants and products. An alternative interpretation of the results based on an approach by Meyer and Nagle removes this problem and the observed linear dependence of ln k(q) on the square root of E degrees (Ni(II)/Ni(III)) in the endergonic region shows that the dominant back electron transfer produces ground-state species. The analysis also leads to an estimate of the (3)Pt(2)(pop)(4)(4)(-)/Pt(2)(pop)(4)(5)(-) potential of 1.29 +/- 0.05 V(vs NHE), in excellent agreement with the previous literature value of 1.34 V.

Stepwise Complexation of Ni(II) and Cu(II) Ions by 6,6'-C-spirobi(cyclam) (cyclam = 1,4,8,11-Tetraazacyclotetradecane), L(1). Syntheses and Redox Chemistry of [M(H(2)L(1))]X(4) (M = Cu(2+), Ni(2+)), [Cu(2)(L(1))]X(4), and [CuNi(L(1))]X(4) (X = ClO(4)(-)) and the X-ray Crystal Structure of [Cu(2)(L(1))](ClO(4))(4).

In aqueous HClO(4), the cation [H(4)(L(1))](4+) where L(1) is 6,6'-C-spirobi(cyclam) (cyclam = 1,4,8,11-tetraazacyclotetradecane), complexes Cu(2+) and Ni(2+) ions in a stepwise fashion to form [M(H(2)L(1))](ClO(4))(4) (M = Cu(2+) and Ni(2+)) from which [CuNi(L(1))](ClO(4))(4) has been prepared selectively. The preparation and the structure of [Cu(2)(L(1))](ClO(4))(4) (empirical formula, C(19)H(44)N(8)Cu(2)Cl(4)O(16); space group, triclinic; P&onemacr;; a = 8.1815(6) Å, b = 12.6098(9) Å, c = 16.6565(12) Å, alpha = 80.3890(10) degrees, beta = 76.5840(10) degrees, gamma = 87.1750(10) degrees, V = 1647.9(2) Å(3), and Z = 2; of the 9531 total reflections collected, 6779 reflections with I > 2sigma(I) on least-squares refinement provided final R(1) = 0.0657 and wR(2) = 0.1424) are also reported. The cyclic voltammograms (1.0 M NaCl, 0.1 M H(+); Pt electrodes; all E(1/2) vs NHE) of [M(H(2)L(1))](4+) (M = Cu(2+) and Ni(2+)) ions show single waves for the Cu(II)/Cu(III) couple (E(1/2) = 0.79 V, irreversible) and the Ni(II)/Ni(III) couple (E(1/2) = 0.56 V, reversible), respectively. In CH(3)CN (0.1 M Et(4)NClO(4)), the [Cu(2)(L(1))](4+) ion shows a reversible wave for the Cu(II)-Cu(II)/Cu(II)-Cu(III) couple ((1)E(1/2) = 1.120 V) and an irreversible wave for the Cu(II)-Cu(III)/Cu(III)-Cu(III) couple ((2)E(1/2) = 1.430 V). Similarly, a reversible wave for the Cu(II)-Ni(II)/Cu(II) -Ni(III) couple ((1)E(1/2) = 0.750 V) and an irreversible wave for the Ni(III)-Cu(II)/Ni(III)-Cu(III) couple ((2)E(1/2) = 1.20 V) are observed in the case of the [Cu(II)Ni(II)(L(1))](4+) ion. The [Cu(2)(L(1))](4+) ion (g( perpendicular) = 2.120, g( parallel) = 2.256 and 2.196, A( parallel) = 150 G, and D( parallel) = 75 G) and the mixed valent species [Cu(II)Ni(III)(L(1))](5+) (for Cu(2+), g( perpendicular) = 2.060, g( parallel) = 2.219, and A( parallel) = 100 G; for Ni(3+) in sulfate media, g( perpendicular) = 2.204 and g( parallel) = 1.967) and [Cu(II)Cu(III)(L(1))](5+) (g(xx)() = 1.982, g(yy)() = 2.155, g(zz)() = 2.386, A(yy)() = 80 G, and A(zz)() = 120 G) show dipolar-dipolar interaction. In the mixed-valent ions, due to strong electrostatic repulsion from either the Ni(III) or Cu(III) ions, significantly smaller A( parallel) (or A(zz)()) values are observed for the Cu(2+) ion compared to 200 G in the mononuclear ions. Also, the [Cu(II)Ni(II)(L(1))](4+) in aqueous HClO(4) and the [Ni(2)(L(1))](4+) ion in CH(3)NO(2) show a tendency to reduce perchlorate very slowly.