Food insecurity during pregnancy in high-income countries, and maternal weight and diet: A systematic review and meta-analysis.

Food insecurity is a well-established obesity driver. Less is known about food insecurity during pregnancy. This review (PROSPERO:CRD42022311669) aimed to explore associations between food insecurity, maternal obesity, gestational weight gain (GWG), and nutrition. Searches included seven databases, gray literature, references, citations, and contacting authors. Observational studies reporting data from January 1st, 2008 to 21 November 2023 in high-income countries were included. Duplicate screening, data extraction, and quality assessments were performed. Random effects meta-analysis estimated odds ratios (OR), mean difference (MD), and 95% confidence intervals (CI). Narrative synthesis was conducted when data could not be pooled. Database searches identified 22,272 results; 20 studies were included (n = 19 North America, n = 1 Europe; n = 32,803 women). Food insecurity significantly increased obesity (OR 1.53 95%CI 1.39, 1.66), but not underweight (OR 1.12 95%CI 0.89, 1.34) or overweight (OR 1.18 95%CI 0.90, 1.46). Food insecurity significantly reduced GWG (MD -0.42 kg 95%CI -0.62, -0.22) and increased inadequate GWG (OR 1.16 95%CI 1.05, 1.28), but not excessive GWG (OR 1.04 95%CI 0.96, 1.13). Diet outcomes were inconsistent, with some evidence of reduced vitamin E and diet quality and increased red/processed meat consumption. Further studies outside of North America are needed to inform practice and policy to support maternal health.

Modeling the extracellular matrix in cell migration and morphogenesis: a guide for the curious biologist.

The extracellular matrix (ECM) is a highly complex structure through which biochemical and mechanical signals are transmitted. In processes of cell migration, the ECM also acts as a scaffold, providing structural support to cells as well as points of potential attachment. Although the ECM is a well-studied structure, its role in many biological processes remains difficult to investigate comprehensively due to its complexity and structural variation within an organism. In tandem with experiments, mathematical models are helpful in refining and testing hypotheses, generating predictions, and exploring conditions outside the scope of experiments. Such models can be combined and calibrated with in vivo and in vitro data to identify critical cell-ECM interactions that drive developmental and homeostatic processes, or the progression of diseases. In this review, we focus on mathematical and computational models of the ECM in processes such as cell migration including cancer metastasis, and in tissue structure and morphogenesis. By highlighting the predictive power of these models, we aim to help bridge the gap between experimental and computational approaches to studying the ECM and to provide guidance on selecting an appropriate model framework to complement corresponding experimental studies.

A systematic scoping review of health-promoting interventions for contact centre employees examined through a behaviour change wheel lens.

PURPOSE: Social determinants of health and poor working conditions contribute to excessive sickness absence and attrition in contact centre advisors. With no recent review conducted, the current scoping review is needed to investigate the volume, effectiveness, acceptability, and feasibility of health-promoting interventions for contact centre advisors. This will inform the adoption and implementation of evidence-based practice, and future research. METHODS: Searches conducted across four databases (MEDLINE, PsycInfo, CINAHL, Web of Science) and reference checking in February 2023 identified health-promoting interventions for contact centre advisors. Extracted and coded data from eligible interventions were systematically synthesised using the nine intervention functions of the Behaviour Change Wheel and behaviour change technique taxonomy. RESULTS: This scoping review identified a low number of high quality and peer-reviewed health-promoting intervention studies for contact centre advisors (28 studies since 2002). Most interventions were conducted in high-income countries with office-based advisors, predominantly using environmental restructuring and training strategies to improve health. Most interventions reported positive effectiveness results for the primary intended outcomes, which were broadly organised into: i) health behaviours (sedentary behaviour, physical activity, smoking); ii) physical health outcomes (musculoskeletal health, visual health, vocal health, sick building syndrome); iii) mental health outcomes (stress, job control, job satisfaction, wellbeing). Few interventions evaluated acceptability and feasibility. CONCLUSION: There is little evidence on the effectiveness, acceptability, and feasibility of health-promoting interventions for contact centre advisors. Evidence is especially needed in low-to-middle income countries, and for remote/hybrid, nightshift, older and disabled advisors.

Interventions in preconception and pregnant women at risk of gestational diabetes; a systematic review and meta-analysis of randomised controlled trials.

BACKGROUND: Women at risk of gestational diabetes mellitus (GDM) need preventative interventions. OBJECTIVE: To evaluate targeted interventions before and during pregnancy for women identified as being at risk of developing GDM. METHODS: Systematic review and meta-analysis conducted following PRISMA guidelines. MEDLINE, EMBASE and the Cochrane Library in addition to reference and citation lists were searched to identify eligible randomised controlled trials (RCTs) utilising risk stratification during the preconception period or in the first/early second trimester. Screening and data extraction were carried out by the authors independently. Quality assessment was conducted based on the Cochrane risk-of-bias tool. Random effects meta-analysis and narrative synthesis were performed. RESULTS: Eighty-four RCTs were included: two during preconception and 82 in pregnancy, with a pooled sample of 22,568 women. Interventions were behavioural (n = 54), dietary supplementation (n = 19) and pharmacological (n = 11). Predictive factors for risk assessment varied; only one study utilised a validated prediction model. Gestational diabetes was reduced in diet and physical activity interventions (risk difference - 0.03, 95% CI 0.06, - 0.01; I2 58.69%), inositol (risk difference - 0.19, 95% CI 0.33, - 0.06; I2 92.19%), and vitamin D supplements (risk difference - 0.16, 95% CI 0.25, - 0.06; I2 32.27%). Subgroup analysis showed that diet and physical activity interventions were beneficial in women with ≥ 2 GDM risk factors (risk difference - 0.16, 95% CI 0.25, - 0.07; I2 11.23%) while inositol supplementation was effective in women with overweight or obesity (risk difference - 0.17, 95% CI 0.22, - 0.11; I2 0.01%). Effectiveness of all other interventions were not statistically significant. CONCLUSIONS: This review provides evidence that interventions targeted at women at risk of GDM may be an effective strategy for prevention. Further studies using validated prediction tools or multiple risk factors to target high-risk women for intervention before and during pregnancy are warranted.

Children's nutritional health and wellbeing in food insecure households in Europe: A qualitative meta-ethnography.

Since the 2008 global financial crisis, there has been a rise in the number of people experiencing food insecurity. Particularly vulnerable are households with children. This systematic review and meta-ethnography of qualitative studies focuses on families' perceptions of food insecurity and how it affects children's nutritional health and wellbeing. Six electronic databases (Medline, Scopus, Web of Science, EMBASE, CINAHL and ASSIA), were searched for studies from European high-income countries between January 2008-July 2021, and supplemented by searches of grey literature databases, relevant websites, examination of reference lists and citation searches. We adhered to PRISMA and eMERGe guidelines to improve the completeness and clarity of meta-ethnographic reporting. Methodological quality of the studies were assessed using the Critical Appraisal Skills Programme qualitative checklist. We identified 11,596 records; we included 19 publications involving 813 participants in total. Data were synthesised according to Noblit & Hare's seven phases of meta-ethnography. We identified four key themes-food and eating practices, awareness, fragility, and networks of care-comprising five sub-themes. Our meta-ethnography provides a progressive 'storyline' of the children's experiences of food insecurity from both caregivers and children's perspectives. We found that children are aware of their family's limited resources and are often active in trying to help their families cope, and that food insecurity adversely impacts children's physical, psychological, and social experiences. Our analysis highlights gaps in knowledge about how food insecurity impacts children's nutritional health and wellbeing. It suggests that future research should prioritise minoritised ethnic communities, children living in temporary accommodation and caregivers of very young children.

APC-driven actin nucleation powers collective cell dynamics in colorectal cancer cells.

Cell remodeling relies on dynamic rearrangements of cell contacts powered by the actin cytoskeleton. The tumor suppressor adenomatous polyposis coli (APC) nucleate actin filaments (F-actin) and localizes at cell junctions. Whether APC-driven actin nucleation acts in cell junction remodeling remains unknown. By combining bioimaging and genetic tools with artificial intelligence algorithms applied to colorectal cancer cell, we found that the APC-dependent actin pool contributes to sustaining levels of F-actin, as well as E-cadherin and occludin protein levels at cell junctions. Moreover, this activity preserved cell junction length and angle, as well as vertex motion and integrity. Loss of this F-actin pool led to larger cells with slow and random cell movement within a sheet. Our findings suggest that APC-driven actin nucleation promotes cell junction integrity and dynamics to facilitate collective cell remodeling and motility. This offers a new perspective to explore the relevance of APC-driven cytoskeletal function in gut morphogenesis.

Experiences and perceptions of nutritional health and wellbeing amongst food insecure women in Europe: A qualitative meta-ethnography.

Since the 2008 global financial crisis, there has been a rise in the number of people experiencing food insecurity. Particularly vulnerable are mothers with young children, pregnant women, and lone parents (the majority of whom are women). This systematic review and meta-ethnography of qualitative studies focused on women's experiences of food insecurity and how it affects their nutritional health and wellbeing. Six electronic databases (Medline, Scopus, Web of Science, EMBASE, CINAHL and ASSIA), were searched from January 1, 2008-July 10, 2021, and supplemented by searches of grey literature databases, relevant websites, examination of reference lists and citation searches. We adhered to PRISMA and eMERGe guidelines to improve the completeness and clarity of meta-ethnographic reporting. Methodological quality of the studies was assessed using the Critical Appraisal Skills Programme qualitative checklist. We identified 11,589 unique records; we included 23 publications reporting data from 22 unique studies involving 647 women. Data were synthesised according to Noblit & Hare's seven phases of meta-ethnography. We identified two key themes - accessing sufficient food and embodying food insecurity - comprising seven sub-themes. Our meta-ethnography provides a progressive 'storyline' of women's experiences of food insecurity. This includes the ways in which women attempt to access sufficient food, are unable to meet their nutritional needs, and the ways in which this is embedded into their everyday lives and embodied in unhealthful physical, social, and mental nutritional health and wellbeing impacts. Our review emphasises that food insecurity directly and tangibly impacts women's nutritional health and wellbeing. It concludes that there needs to be greater recognition of the psychosocial impact of food insecurity on vulnerable women in addition to its impact on their nutritional health and wellbeing.

Food insecurity among pregnant women living in high-income countries: a systematic review.

BACKGROUND: Food insecurity is an increasingly important public health concern in high-income countries following the 2008 global financial crash, and recently with the COVID-19 pandemic. Food insecurity has been understood as a highly gendered issue, affecting more women than men. As women have more complex nutritional needs because of their menstrual cycle, pregnancy, and breastfeeding, the nutritional impact of food insecurity is also greater for women than for men. This systematic review aims to explore pregnant women's experiences of food insecurity in high-income countries and to understand how food insecurity affects their health, wellbeing, diet, and nutrition. METHODS: We did a systematic review following PRISMA reporting guidelines. A comprehensive search strategy was developed using search terms such as "food insecurity" and "pregnancy outcomes". We searched seven databases (MEDLINE, Embase, Scopus, Web of Science, PsychInfo, ASSIA, and CINAHL), grey literature, reference lists, and citations, as well as contacted authors. No language restrictions were used, and only studies primarily containing data collected from Jan 1, 2008, onwards were included. Database searches were completed in April 2022; supplementary searches are ongoing. Inclusion criteria is based on PECOS. Screening, data extraction, and quality assessment were done by two authors independently. This systematic review is registered on PROSPERO, number CRD42022311669. FINDINGS: 27 studies met the inclusion criteria, with all studies published between 2015 and 2022. 24 (89%) of 27 studies were done in the USA, two (7%) in Canada, and one (4%) in the UK. Outcomes reported include dietary intake or dietary quality during pregnancy (seven [26%] of 27), gestational weight gain (seven [26%]), mental health (five [19%]), pregnancy outcomes including pregnancy complications, preterm birth, or birthweight (five [19%]), and other health outcomes or combination of nutrition, health, and wellbeing (three [11%]). Evidence synthesis is ongoing and will be complete by August, 2022. INTERPRETATION: This systematic review suggests that food insecurity experienced during pregnancy was associated with negative health and nutrition outcomes. The rigorous searches are strengths of this study. A limitation is the restricted focus on studies done from 2008 onward. More research to guide efficient interventions that address food insecurity among pregnant women is needed. FUNDING: None.

Food insecurity and the nutritional health and well-being of women and children in high-income countries: protocol for a qualitative systematic review.

INTRODUCTION: Since the global financial crises of 2008, there has been a rise in the number of people experiencing food insecurity. The COVID-19 pandemic has exacerbated this. Many more are unable to afford or access food of sufficient quality and quantity to enable good health and well-being. Particularly vulnerable are mothers with young children, pregnant women and lone parents (the majority of whom are women). This review aims to understand experiences of food insecurity and how it affects women and children's nutritional health and well-being, focusing on experiences explicitly related to nutrition. Findings will help guide health policy and practice to support food-insecure women and children from high-income countries. METHODS AND ANALYSIS: A systematic review and meta-ethnography exploring (1) food-insecure women's own accounts of their nutritional health and (2) food-insecure household's accounts of their children's nutritional health. Six major databases (MEDLINE, Scopus, Web of Science, EMBASE, CINAHL and ASSIA), grey literature databases and relevant stakeholder websites will be searched from 1 January 2008 to 30 March 2021. Reference list and citation searches will supplement electronic database searches. Outcomes of interest are accounts of nutrition and nutritional health, including diet, food practices, infant feeding practices and physical and mental health. The review will follow the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocol guidelines, but as this is a meta-ethnography it will adhere to eMERGe Reporting Guidance for synthesis and writing findings of the final report. Critical Appraisal Skills Programme qualitative checklist will assess the quality of studies. A meta-ethnographic analysis will be conducted for all included studies. ETHICS AND DISSEMINATION: As a qualitative systematic review, without primary data collection, ethical approval will not be required. Findings will be submitted for peer-reviewed publication. PROSPERO REGISTRATION NUMBER: CRD42020214159.

Effects of social security policy reforms on mental health and inequalities: A systematic review of observational studies in high-income countries.

Evidence increasingly shows that changes to social security policies can affect population mental health. Thus, in the context of rising burden of mental illness, it is of major importance to better understand how expansions and contractions to the social security system may impact on mental health of both adults and children. The aim of this systematic review is to provide a synthesis of observational literature on the effects on mental health and inequalities in mental health of social security reforms. We conducted a systematic review of quantitative observational studies of specific national and regional social security policy changes in high-income countries and summarised the mental health effects of these policies. We searched seven electronic databases, including Medline, PsychInfo, Embase, CINAHL, ASSIA (Proquest), Scopus and Research Papers in Economics from January 1979 to June 2020. We included both objective and subjective mental health and wellbeing measures. The study quality was assessed using the Validity Assessment tool for econometric studies. We identified 13,403 original records, thirty-eight of which were included in the final review. Twenty-one studies evaluated expansionary social security policies and seventeen studies evaluated contractionary policies. Overall, we found that policies that improve social security benefit eligibility/generosity are associated with improvements in mental health, as reported by fourteen of the included studies. Social security policies that reduce eligibility/generosity were related to worse mental health, as reported by eleven studies. Ten studies found no effect for either policies contracting or expanding welfare support. Fourteen studies also evaluated the impact on mental health inequalities and found that contractionary policies tend to increase inequalities whereas expansionary policies have the opposite effect. Changes in social security policies can have significant effects on mental health and health inequalities across different recipient groups. Such health effects should be taken into account when designing future social policy reforms.

COVID-19 and how the wearing of face coverings can affect those with an experience of trauma.

WHAT IS KNOWN ON THE SUBJECT?: With the ongoing and possible evolving use of face coverings as a public health protection measure against the transmission of COVID-19, this is likely to be an ongoing challenge for those who find their use challenging. The wearing of face coverings following trauma is likely to be of ongoing relevance, making this an area that would benefit from further research. WHAT THIS PAPER ADDS TO EXISTING KNOWLEDGE?: The authors present their personal and professional experiences as a means of highlighting the difficulties that can be faced as a result of the use of face coverings. The window of tolerance helps to understand the difficulties that can be caused by wearing face coverings and provides a visual means of conceptualizing the cognitive, behavioural, physiological and emotional reactions that can occur as a result of their use. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: This paper provides an awareness of the link between trauma and the wearing of face coverings, and how their use could be re-traumatizing for those accessing services. This topic is relevant across all sectors where it is only just beginning to be acknowledged that for many, particularly those with experiences of interpersonal trauma, difficulties can arise due to the use of face coverings. The sharing of grounding techniques and an introduction to the window of tolerance provides a means of collaboratively developing skills and developing a shared understanding of the difficulties associated with the use of face coverings.

Investigating the relationship between changes in social security benefits and mental health: a protocol for a systematic review.

INTRODUCTION: Poor mental health is one of the greatest causes of disability in the world. Evidence increasingly shows that population mental health may be influenced by national social security policies. This systematic review aims to establish the relationship between social security and mental health in order to help inform recommendations for policy-makers, practitioners and future research. METHODS AND ANALYSIS: A systematic review of quantitative observational studies investigating mental health outcomes related to changes in social security policies will be conducted. Six major databases, including Medline, PsychInfo, Embase, Cumulative Index to Nursing and Allied Health Literature, Applied Social Sciences Index Abstracts and Scopus, as well as Research Papers in Economics will be searched from January 1979 to April 2020. The electronic database searches will be supplemented by reference and citation searches as well as hand-searching of key journals. The outcomes of interest are objective or subjective mental health outcomes, including stress, anxiety, depression, self-reported mental health scores, subjective well-being and suicide. Study selection will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, and the quality of the studies will be assessed by the validity assessment framework designed for appraising econometric studies. A narrative synthesis will be conducted for all included studies. If data permit, study findings will be synthesised by conducting a meta-analysis. ETHICS AND DISSEMINATION: As it will be a systematic review, without primary data collection, there will be no requirement for ethical approval. Findings will be disseminated through peer-reviewed publications and in various media, for example, conferences or symposia. PROSPERO REGISTRATION NUMBER: CRD42019154733.

Sensitised near-infrared luminescence from lanthanide(III) centres using Re(I) and Pt(II) diimine complexes as energy donors in d-f dinuclear complexes based on 2,3-bis(2-pyridyl)pyrazine.

The luminescent transition metal complexes [Re(CO)(3)Cl(bppz)] and [Pt(CC-C(6)H(4)CF(3))(2)(bppz)] [bppz = 2,3-bis(2-pyridyl)pyrazine], in which one of the diimine binding sites of the potentially bridging ligand bppz is vacant, have been used as 'complex ligands' to make heterodinuclear d-f complexes by attachment of a {Ln(dik)(3)} fragment (dik = a 1,3-diketonate) at the vacant site. When Ln = Pr, Nd, Er or Yb the lanthanide centre has low-energy f-f excited states capable of accepting energy from the (3)MLCT excited state of the Pt(II) or Re(I) centre, quenching the (3)MLCT luminescence and affording sensitised lanthanide(III)-based luminescence in the near-IR region. UV/Vis and luminescence spectroscopic titrations allowed measurement of (i) the association constants for binding of the {Ln(dik)(3)} fragment at the vacant diimine site of [Re(CO)(3)Cl(bppz)] or [Pt(CC-C(6)H(4)CF(3))(2)(bppz)], and (ii) the degree of quenching of the (3)MLCT luminescence according to the nature of the Ln(III) centre. In all cases Nd(III) was found to be the most effective of the series at quenching the (3)MLCT luminescence of the d-block component because the high density of f-f excited states of the appropriate energy make it a particularly effective energy-acceptor.

Dinuclear Bis(1,2-diaryl-1,2-ethylenedithiolato)iron complexes: [FeIII2(L)4]n (n = 2-, 1-, 0, 1+).

The electronic structures of four members of the electron-transfer series [Fe2(1L)4]n (n = 2-, 1-, 0, 1+) have been elucidated in some detail by electronic absorption, IR, X-band electron paramagnetic resonance (EPR), and Mössbauer spectroscopies where (1L)(2-) represents the ligand 1,2-bis(4-tert-butylphenyl)-1,2-ethylenedithiolate(2-) and (1L*)- is its pi-radical monoanion. It is conclusively shown that all redox processes are ligand-centered and that high-valent iron(IV) is not accessible. The following complexes have been synthesized: [FeIII2(1L*)2(1L)2]0 (1), [FeIII2(2L*)2(2L)2].2CH2Cl2 (1') where (2L)(2-) is 1,2-bis(p-tolyl)-1,2-ethylenedithiolate(2-) and (2L*)- represents its pi-radical monoanion, [Cp2Co][FeIII2(1L*))(1L)3].4(toluene).0.5Et2O (2), and [Cp2Co]2[FeIII2(1L)4].2(toluene) (3). The crystal structures of 1' and 2 have been determined by single-crystal X-ray crystallography at 100 K. The ground states of complexes have been determined by temperature-dependent magnetic susceptibility measurements and EPR spectroscopy: 1' and 1 are diamagnetic (S(t) = 0); 2 (S(t) = 1/2); 3 (S(t) = 0); the monocation [Fe(III)2(1L*)3(1L)]+ possesses an S(t) = 1/2 ground state (S(t) = total spin ground state of dinuclear species). All species contain pairs of intermediate-spin ferric ions (S(Fe) = 3/2), which are strongly antiferromagnetically coupled (H = -2JS(1).S(2), where S1 = S2 = 3/2 and J = approximately -250 cm(-1)).

Syntheses and crystal structures of dinuclear complexes containing d-block and f-block luminophores. Sensitization of NIR luminescence from Yb(III), Nd(III), and Er(III) centers by energy transfer from Re(I)- and Pt(II)-bipyrimidine metal centers.

Mononuclear complexes [Re(bpym)(CO)(3)Cl] and [Pt(bpym)(CC-C(6)H(4)CF(3))(2)] (bpym = 2,2'-bipyrimidine), in which one of the bipyrimidine sites is vacant, have been used as "complex ligands" to prepare heterodinuclear d-f complexes in which a lanthanide tris(1,3-diketonate) unit is attached to the secondary bipyrimidine site to evaluate the ability of d-block chromophores to act as antennae for causing sensitized near-infrared (NIR) luminescence from adjacent lanthanide(III) centers. The two sets of complexes so prepared are [Re(CO)(3)Cl(mu-bpym)Ln(fod)(3)] (abbreviated as Re-Ln; where Ln = Yb, Nd, Er) and [(F(3)C-C(6)H(4)-CC)(2)Pt(mu-bpym)Ln(hfac)(3)] (abbreviated as Pt-Ln; where Ln = Nd, Gd). Members of both series have been structurally characterized; the metal-metal separation across the bipyrimidine bridge is approximately 6.3 A in each case. In these complexes, the (3)MLCT (MLCT = metal to ligand charge-transfer) luminescences of the mononuclear [Re(bpym)(CO)(3)Cl] and [Pt(bpym)(CC-C(6)H(4)CF(3))(2)] complexes are quenched by energy transfer to those lanthanides (Ln = Yb, Nd, Er) that have low-lying f-f states capable of NIR luminescence; as a result, sensitized NIR luminescence is seen from the lanthanide center following excitation of the d-block unit. In the solid state, quenching of the luminescence from the d-block chromophore is complete, indicating efficient d --> f energy transfer, as a result of the short metal-metal separation across the bipyrimidine bridge. In a CH(2)Cl(2) solution, partial dissociation of the dinuclear complexes into the mononuclear units occurs, with the result that some (3)MLCT luminescence is observed from mononuclear [Re(bpym)(CO)(3)Cl] or [Pt(bpym)(CC-C(6)H(4)CF(3))(2)] present in the equilibrium mixture. Solution UV-vis and luminescence titrations, carried out by the addition of portions of Ln(fod)(3)(H(2)O)(2) or Ln(hfac)(3)(H(2)O)(2) to the d-block complex ligands, indicate that binding of the lanthanide tris(1,3-diketonate) unit at the secondary bipyrimidine site to give the d-f dinuclear complexes occurs with an association constant of ca. 10(5) M(-)(1).

Complexes of substituted derivatives of 2-(2-pyridyl)benzimidazole with Re(I), Ru(II) and Pt(II): structures, redox and luminescence properties.

N,N'-Chelating ligands based on the 2-(2-pyridyl)benzimidazole (PB) core have been prepared with a range of substituents (phenyl, pentafluorophenyl, naphthyl, anthracenyl, pyrenyl) connected to the periphery via alkylation of the benzimidazolyl unit at one of the N atoms. These PB ligands have been used to prepare a series of complexes of the type [Re(PB)(CO)(3)Cl], [Pt(PB)(CCR)(2)](where -CCR is an acetylide ligand) and [Ru(bpy)(2)(PB)][PF(6)](2)(bpy = 2,2'-bipyridine). Six of the complexes have been structurally characterised. Electrochemical and luminescence studies show that all three series of complexes behave in a similar manner to the analogous complexes with 2,2'-bipyridine in place of PB. In particular, all three series of complexes show luminescence in the range 553-605 nm (Pt series), 620-640 nm (Re series) and 626-645 nm (Ru series) arising from the (3)MLCT state, with members of the Pt(II) series being the most strongly emissive with lifetimes of up to 500 ns and quantum yields of up to 6% in air-saturated CH(2)Cl(2) at room temperature. In the Re and Ru series there was clear evidence for inter-component energy-transfer processes in both directions between the (3)MLCT state of the metal centre and the singlet and triplet states of the pendant organic luminophores (naphthalene, pyrene, anthracene). For example the pyrene singlet is almost completely quenched by energy transfer to a Re-based MLCT excited state, which in turn is completely quenched by energy transfer to the lower-lying pyrene triplet state. For the analogous Ru(II) complexes the inter-component energy transfer is less effective, with (1)anthracene --> Ru((3)MLCT) energy transfer being absent, and Ru((3)MLCT)-->(3)anthracene energy transfer being incomplete. This is rationalised on the basis of a greater effective distance for energy transfer in the Ru(II) series, because the MLCT excited states are localised on the bpy ligands which are remote from the pendant aromatic group; in the Re series in contrast, the MLCT excited states involve the PB ligand to which the pendant aromatic group is directly attached, giving more efficient energy transfer.

Self-asssembly of a molecular M8L12 cube having S6 symmetry.

Reaction of the bis-bidentate ligand L1, having two bidentate pyrazolyl-pyridine termini, with Co(II) or Zn(II) results in formation of the complexes [M8(L1)12]X16 (X = perchlorate or tetrafluoroborate); [Zn8(L1)2](ClO4)16 has been structurally characterised and is a cube with a metal ion at each corner, a bridging ligand along each edge, and an anion in the central cavity.

Mono- and dinuclear ruthenium carbonyl complexes with redox-active dioxolene ligands: electrochemical and spectroscopic studies and the properties of the mixed-valence complexes.

The mononuclear complex [Ru(PPh(3))(2)(CO)(2)(L(1))] (1; H(2)L(1) = 7,8-dihydroxy-6-methoxycoumarin) and the dinuclear complexes [[Ru(PPh(3))(2)(CO)(2)](2)(L(2))][PF(6)] [[2][PF(6)]; H(3)L(2) = 9-phenyl-2,3,7-trihydroxy-6-fluorone] and [[Ru(PBu(3))(2)(CO)(2)](2)(L(3))] (3; H(4)L(3) = 1,2,3,5,6,7-hexahydroxyanthracene-9,10-dione) have been prepared; all complexes contain one or two trans,cis-[Ru(PR(3))(2)(CO)(2)] units, each connected to a chelating dioxolene-type ligand. In all cases the dioxolene ligands exhibit reversible redox activity, and accordingly the complexes were studied by electrochemistry and UV/vis/NIR, IR, and EPR spectroscopy in their accessible oxidation states. Oxidation of 1 to [1](+) generates a ligand-centered semiquinone radical with some metal character as shown by the IR and EPR spectra. Dinuclear complexes [2](+) and 3 show two reversible ligand-centered couples (one associated with each dioxolene terminus) which are separated by 690 and 440 mV, respectively. This indicates that the mixed-valence species [2](2+) has greater degree of electronic delocalization between the ligand termini than does [3](+), an observation which was supported by IR, EPR, and UV/vis/NIR spectroelectrochemistry. Both [2](2+) and [3](+) have a solution EPR spectrum consistent with full delocalization of the unpaired electron between the ligand termini on the EPR time scale (a quintet arising from equal coupling to all four (31)P nuclei); [3](+) is localized on the faster IR time scale (four CO vibrations rather than two, indicative of inequivalent [Ru(CO)(2)] units) whereas [2](2+) is fully delocalized (two CO vibrations). UV/vis/NIR spectroelectrochemistry revealed the presence of a narrow, low-energy (2695 nm) transition for [3](+) associated with the catecholate --> semiquinone intervalence transition. The narrowness and solvent-independence of this transition (characteristic of class III mixed-valence character) coupled with evidence for inequivalent [Ru(CO)(2)] termini in the mixed-valence state (characteristic of class II character) place this complex at the class II-III borderline, in contrast to [2](2+) which is clearly class III.

Sensitized near-infrared emission from complexes of YbIII, NdIII and ErIII by energy-transfer from covalently attached PtII-based antenna units.

A series of dinuclear platinum(II)-lanthanide(iii) complexes has been prepared in which a square-planar Pt(II) unit, either [(PPh(3))(2)Pt(pdo)] (H(2)pdo=5,6-dihydroxyphenanthroline) or [Cl(2)Pt(dppz)] [dppz=2,3-bis(2-pyridyl)pyrazine], is connected to a Ln(dik)(3) unit ("dik"=a 1,3-diketonate ligand). The mononuclear complexes [(PPh(3))(2)Pt(pdo)] and [Cl(2)Pt(dppz)] both have external, vacant N,N-donor diimine-type binding sites that react with various [Ln(dik)(3)(H(2)O)(2)] units to give complexes [(PPh(3))(2)Pt(micro-pdo)Ln(tta)(3)] (series A; Htta=thenoyltrifluoroacetone), [Cl(2)Pt(micro-dppz)Ln(tta)(3)] (series B); and [Cl(2)Pt(micro-dppz)Ln(btfa)(3)] (series C; Hbtfa=benzoyltrifluoroacetone); in all of these the lanthanide centres are eight-coordinate. The lanthanides used exhibit near-infrared luminescence (Nd, Yb, Er). Crystal structures of members of each series are described. In all complexes, excitation into the Pt-centred absorption band (at 520 nm for series A complexes; 440 nm for series B and C complexes) results in characteristic near-IR luminescence from the Nd, Yb or Er centres in both the solid state and in CH(2)Cl(2), following energy-transfer from the Pt antenna chromophore. This work demonstrates how d-block-derived chromophores, with their intense and tunable electronic transitions, can be used as sensitisers to achieve near-infrared luminescence from lanthanides in suitably designed heterodinuclear complexes based on simple bridging ligands.

Sensitised near-infrared emission from lanthanides using a covalently-attached Pt(II) fragment as an antenna group.

In a series of heterodinuclear complexes in which a Pt(PPh3)2(catecholate) chromophore is covalently linked to a lanthanide tris(diketonate) unit, sensitised near-IR emission from Yb(III), Nd(III) and Er(III) occurs on excitation of the Pt(II) chromophore at 520 nm.