Health surveillance for SARS-CoV-2: infection spread and vaccination coverage in the schools of Modena province, Italy

Introduction

In Italy, over 4.8 million individuals aged 0-19 years have been infected with SARS-CoV-2. This study aims to evaluate the spread of SARS-CoV-2 within schools in Modena province and the influence of anti-SARS-CoV-2 vaccination coverage.

Methods

We performed a survey in the period 1 September-15 December 2021, involving student population aged 0-19 years and related teachers screened for SARS-CoV-2 infection using nasopharyngeal swab after the detection of an index case within their class. During the study period, vaccination against SARS-CoV-2 was actively offered to all subjects aged ≥12 years.

Results

A total of 13,934 subjects were tested, 12,534 students and 1,400 teachers (594 classes). We identified a total of 594 and 779 index and secondary cases, respectively. We found that 9.8% of students and 10.6% of teachers were positive for SARS-CoV-2. Overall at the test time, 32.5% were vaccinated with at least one dose of anti-SARS-CoV-2 vaccine. Among secondary cases, 7.8% were vaccinated compared to 34.9% among negative tested subjects. A higher secondary attack rate was for non-vaccinated subjects rather than vaccinated ones (8.1% vs. 1.4%). Higher secondary attack rates were reported for subjects attending infant and primary school (5.9 and 9.6%, respectively). Lower secondary attack rates were for those who attended middle school (4.9%) and especially high school (1.7%).

Conclusion

Our results highlight the differential spread of the infection within various educational settings and that the vaccination, available in the study period for the population aged ≥12, have mitigated SARS-CoV-2 spread in high and middle schools.

Use of a mHealth System to Improve Antenatal Care in Low and Lower-Middle Income Countries: Report on Patients and Healthcare Workers' Acceptability in Tanzania

Antenatal care (ANC) is considered a cornerstone of reproductive health programmes, but many women face difficulties in accessing these services, particularly in some sub-Saharan African countries, such as Tanzania. This study aimed to test ANC visit acceptability using mHealth system PANDA (Pregnancy And Newborn Diagnostic Assessment) in the Mufindi district (Tanzania). We investigated the ANC visit acceptability of pregnant women and healthcare workers (HCWs) in an intervention area using the PANDA system compared with a control area. An ad hoc questionnaire was administered to pregnant women in an implementation area (n = 52) and in a control area (n = 46). In the implementation area, group interviews with 50 pregnant women were conducted and five HCWs evaluated ANC visits through a questionnaire. The implementation group was significantly more satisfied with the ANC visit compared with the control group. All the 52 women and the HCWs declared that PANDA icons were useful in understanding and remembering the provided information and the PANDA app was able to improve the ANC quality and to positively influence the relationship of HCWs and pregnant women. HCWs reported that the PANDA app was "easy-to-use" and "able to improve the adherence to ANC WHO recommendations". In underserved areas, many pregnant women could benefit from the PANDA system increasing their access to high-quality ANC and overcoming language and/or literacy barriers.

Characteristics and risk factors of isolated and quarantined children and adolescents during the first wave of SARS-CoV-2 pandemic: A cross-sectional study in Modena, Northern Italy

Background and aim:

In early 2020, SARS-CoV-2 was declared a pandemic by the WHO and Italy was one of the first and most severely affected country in Europe. Despite the global interest about COVID-19 pandemic, several aspects of this infection are still unclear, especially in pediatric population. This study aims to investigate the characteristics of the isolated or quarantined children and adolescents followed by the Public Health Department of the Italian province of Modena during the first wave of COVID-19.

Methods:

The study population included all non-adult subjects aged 0-18 years who underwent isolation or quarantine during the first wave of SARS-CoV-2 pandemic from February 24 to June 18, 2020 in Modena province, Northern Italy.

Results:

In Modena province, 1230 children and adolescents were isolated in case of SARS-CoV-2 infection (6.3%), or quarantined due to close contact with confirmed cases (88.7%) or travelling from a high-risk area (5.0%). Among 349 individuals who underwent swab testing, 294 (84.2%) reported close contact with an infected cohabiting relative and 158 (45.3%) were symptomatic. Among all tested subjects, 78 (22.4%) resulted positive, with a higher proportion of symptomatic subjects compared with the SARS-CoV-2-negative (78.2% vs. 35.8%). Fever was mostly present in SARS-CoV-2-positive children (48.7% vs. 12.6%). Both anosmia (58.3% vs. 41.7%) and dysgeusia (54.5% vs. 45.5%) had only slightly higher frequency in SARS-CoV-2-positive.

Conclusions:

These findings allow to expand the knowledge regarding characteristics of non-adult subjects isolated or quarantined during the first wave of SARS-CoV-2 pandemic. (www.actabiomedica.it)

Physical and Sedentary Activities and Childhood Overweight/Obesity: A Cross-Sectional Study among First-Year Children of Primary Schools in Modena, Italy

Children obesity is a serious public health issue. This study aimed to investigate physical/sedentary activities of first-year primary schools children in Modena, and their association with overweight/obesity and dietary habits of children and family characteristics to identify the risk factors for unhealthy lifestyles. Child physical/sedentary activities were gathered through an anonymous questionnaire administered to parents, as well as family characteristics and weight/height of child and parents. Logistic regression models, eventually adjusted for parents' sociodemographic characteristics, were used to analyze data. Questionnaires were delivered by 660 families (74.2%), of which 72 without anthropometric data were excluded. Three out of four children spent in physical activities less than 7 h/week, while 63.9% dedicated to sedentary activities two or more hours/day. From multivariate analysis, the habit significantly affecting children's overweight/obesity was spending time on tablets/Personal Computers/mobile phones/videogames. Higher parental education level resulted in a protective factor for implementing unhealthy lifestyles in terms of time dedicated to physical/sedentary activities. Our results suggest the need of interventions to increase time for physical activity and to promote a responsible use of digital media involving the entire families to reach all parents regardless of their education and nationality with a possible relapse on other family members.

Risk Factors for Overweight and Obesity in Children Attending the First Year of Primary Schools in Modena, Italy

Over the last four decades, childhood overweight/obesity has dramatically increased, becoming a significant public health concern. The main aims of this study were to investigate the prevalence of overweight/obesity among first-year primary schools children in Modena and to identify the associated risk factors. Data were collected on the socio-demographic characteristics of family and weight, height, dietary habits and sedentary behaviours of the children, and on the parents' perception of their child's weight status, through an anonymous questionnaire administered to parents. The questionnaires were delivered by 660 out of 890 (74.2%) families, and after excluding those without anthropometric data, 588 children were included in the study. The prevalence of overweight/obesity among the children was 25.2%, significantly lower in children born to parents with a high education, and higher among children born to foreign parents and overweight/obese mothers. The multivariable analysis showed that the children most likely to become overweight/obese were those who skipped breakfast (OR 2.3, 95%CI 1.3-4.2) and/or mid-morning snacks (OR 3.2, 95%CI 1.5-6.5). Breakfast consumption was positively associated with higher parental education levels, whereas skipping mid-morning snacks is more frequent among children born to foreign parents and overweight/obese mothers. Moreover, 84.7% of the parents of overweight/obese children underestimated their child's weight status. One in four 6-7 year-old children is already overweight or obese. Childhood overweight/obesity is significantly associated with unhealthy lifestyles and family lifestyle. It is therefore essential to implement public health intervention programs aimed at both parents and children, in order to promote healthy lifestyles in early childhood.

Telemedicine system for improving maternal and neonatal health: an interventional trial in Tanzania

Background

In Tanzania, maternal and neonatal mortality is still high, mainly due to poor quality of Antenatal Care (ANC) and Post Natal Care (PNC) services. PANDA (Pregnancy And Newborn Diagnostic Assessment) is a telemedicine system that uses mobile technology to perform adequate ANC/PNC visits according to WHO recommendations. Two pilot studies showed that PANDA is efficient in providing high-quality ANC and facilitating the continuity of care for underserved communities.

This project aims at testing the impact of PANDA in Tanzania for improving the adherence to both ANC and PNC WHO protocols.

Methods

This case-control study is conducted in two different areas of the Mufindi district, Tanzania. The PANDA system includes: - solar backpack containing instrumentation for communicable and non-communicable diseases screening; smartphone with an icon-based application, including 5 modules: socio-demographic information, medical history, clinical screening, health education and birth plan, postnatal care;hospital database with the data collected during the visits.

Results

At present, 405 women (1,066 ANC visits) were recruited in the implementation site and 200 in the control site. The preliminary results show that 60% of women attended ≥ 2 ANC visits in the implementation site. In this area, 52 women were found positive for HIV and 4 for syphilis. Data collection in both the sites is ongoing.

Conclusions

PANDA system allows the creation of electronic patient records and the identification of the high-risk pregnancies. The collection of population data is useful for health planning policies. The easy-to-use and easy-to-understand graphic interface overcomes language and literacy barriers and facilitates comprehension of women and compliance to visits. This can improve the quality of ANC/PNC services with an expected reduction in maternal and neonatal mortality.

Key messages

PANDA system increases access to high-quality ANC for pregnant women in low-income countries, improving the adherence to WHO recommendations. The telemedicine system PANDA is a useful tool for public health policy-makers, as it allows the collection of previously unavailable population data.

Relationship between physical/sedentary activities and overweight/obesity in Modena primary schools

Background

Childhood overweight/obesity can be influenced by food habits, but also by poor physical activity and excessive use of screens. The aim of this study was to investigate physical exercise and sedentary behaviours of children attending the first year of primary schools in Modena, and their association with weight status of children and characteristics of family.

Methods

We involved 890 children attending the first classes of 15 primary schools in Modena. The physical and sedentary activities of child were examined through an anonymous questionnaire administered to the parents. Sociodemographic characteristics of family, weight and height of child and parents were also collected. Univariate logistic regression models, eventually adjusted for parents' sociodemographic characteristics, were used to analyse data.

Results

Filled questionnaires were 660 out of 890 families (74.2%), of which 72 without anthropometric data were excluded. The prevalence of overweight/obesity was 25.2% without difference of gender. Less than 25% of children did physical activity per ≥7 hours per week; most children (about 40%) did 2 to 4 hours per week. There was no association between time spent in physical activity and overweight/obesity of children. From multivariate analysis, the habit significantly affecting children's overweight/obesity was spending time on tablets, PCs, mobile phones, videogames (OR = 2.2, CI 95%: 1.4-3.6). Children screen time ≥2 hours daily (63.9%) was associated with parents' low education level and father's weight status.

Conclusions

Our results suggest the need of educational interventions aimed to increase time spent in physical activity, and to promote a responsible use of digital media, by actively involving both children and parents.

Key messages

Children screen time ≥2 hours daily is strongly associated with childhood overweight/obesity. High education level of parents can positively affect lifestyles of their children.

Evaluation of Occupational Exposure to Perchlorethylene in a Group of Italian Dry Cleaners Using Noninvasive Exposure Indices

Recent data suggest a general trend in decreased occupational exposure to perchlorethylene (PCE) in the dry-cleaning sector. The aims of this study were to confirm this trend to lower exposure levels in a group of Italian dry cleaners and to evaluate the current occupational PCE exposure in these works using noninvasive biological indices. Environmental exposure was assessed by personal sampling in 60 operators working in 21 dry cleaning shops in North Italy. PCE in the exhaled alveolar air (PCEalv), urinary concentration of PCE and of trichloroacetic acid (TCA) (PCEu and TCAu respectively), were measured as biological exposure indices. Median PCE environmental concentration in the whole sample was 10.6 mg/m3 (i.e., less than the 25% of the levels measured in the same area in a previous study). All values were less than 10% of the occupational limits. PCEu measured in samples collected at the end of the work shift resulted the biological markers having the strongest correlation with environmental PCE (r = 0.81). PCEalv also resulted in a high correlation (r = 0.66), while a lower correlation was found for TCAu measured at the end shift (r = 0.32). According to our results, PCEu can be proposed as a valid, noninvasive, and easily reliable exposure index to evaluate PCE exposure at the low levels currently observed in dry cleaners, therefore representing a promising alternative to invasive blood sample collections needed to determine PCE blood concentration.

Maternal pregestational diabetes and risk of acute lymphoblastic leukemia in the offspring: A population-based study in Northern Italy

INTRODUCTION

This population-based study aims to evaluate the association between maternal pregestational diabetes and risk of acute lymphoblastic leukemia (ALL) in the offspring.

METHODS

All 241,958 children born in three Northern Italy provinces 1998-2010 were followed from birth until first cancer diagnosis (National Childhood Cancer Register), age 15 years, or 31 December 2017. We computed hazard ratio (HR) and 95% CI of ALL in relation to the presence of maternal diabetes through Cox proportional regression models.

RESULTS

We observed 145 cases of ALL, with a higher incidence in children born to women with pregestational diabetes compared to the others (12.4 vs 4.6). Adjusted hazard ratio of ALL was 2.6 (CI, 0.6-10.5) for maternal diabetes.

DISCUSSION

We estimated higher risks of ALL in the offspring of women with pregestational diabetes. These results are consistent with previous findings and compatible with a role of prenatal glycaemic environment in childhood cancer aetiology.

Joint Effect of Maternal Tobacco Smoking and Pregestational Diabetes on Preterm Births and Congenital Anomalies: A Population-Based Study in Northern Italy

Smoking and pregestational diabetes (PGD) are recognized risk factors for adverse pregnancy outcomes, but to date, no population-based study has investigated their joint effects. Using hospital discharges, we identified all women with PGD delivering in Emilia-Romagna region during 2007-2010 matched 1 : 5 with parturients without diabetes. Our study endpoints were preterm births and congenital anomalies. We measured interaction between PGD and maternal smoking, by calculating excess prevalence and prevalence ratio due to interaction, relative excess risk due to interaction (RERI), attributable proportion (AP), and the synergy index (S). Analyses were performed in the overall study population and in the subgroup whose PGD was validated through diabetes registers. The study included 992 women with PGD (10.5% smokers) and 4788 comparison women (11.9% smokers). The effects of PGD and maternal tobacco smoking were greater than additive for both preterm birth (excess prevalence due to interaction = 11.7%, excess ratio due to interaction = 1.5, RERI = 2.39, AP = 0.51, S = 2.82) and congenital anomalies (excess prevalence due to interaction = 2.2%, excess ratio due to interaction = 1.3, RERI = 1.33, AP = 0.49, S = 5.03). Joint effect on both endpoints was confirmed in the subgroup whose PGD status was validated. In conclusion, we found that maternal tobacco smoking and PGD intensify each other's effect on preterm birth and congenital anomalies.

Impact of Referral Sources and Waiting Times on the Failure to Quit Smoking: One-Year Follow-Up of an Italian Cohort Admitted to a Smoking Cessation Service

In Italy, the National Health Service offers specialized evidence-based support to smokers who would like to quit through smoking cessation (SC) services. We conducted a two-year prospective study, involving all 288 subjects treated for smoking cessation at the SC service of Reggio Emilia, to assess the association of referral sources and waiting times with the risk of treatment failure, by following participants up to one year after the quit date. We performed Cox-regression analysis, including demographic and smoking-related characteristics as confounding variables. The treatment failure rate at 12 months was 59.4% (171/288), including only 12 subjects lost to follow-up. The main mode of entry was self-referral (42.4%), followed by 32.6% from general practice, 17.4% from hospital and 7.6% from other sources. Only 27.8% participants were involved in the SC-program within 60 days of the first contact, as the guidelines suggest. The risk of treatment failure at 12 months showed little association with the type of referral source, while it correlated with waiting times ≥ 60 days (hazard ratio = 1.59; 95% confidence interval 1.10⁻2.29). This study provides evidence of long-term high quit rates from a SC service, with few subjects lost to follow-up and biochemical verification of almost all abstinent subjects. Timeliness in care provision could further improve the outcome.

Impact of Pre-Analytical Time on the Recovery of Pathogens from Blood Cultures: Results from a Large Retrospective Survey

BACKGROUND

Prompt identification of bloodstream pathogens is essential for optimal management of patients. Significant changes in analytical methods have improved the turnaround time for laboratory diagnosis. Less attention has been paid to the time elapsing from blood collection to incubation and to its potential effect on recovery of pathogens. We evaluated the performance of blood cultures collected under typical hospital conditions in relation to the length of their pre-analytical time.

METHODS

We carried out a large retrospective study including 50,955 blood cultures collected, over a 30-month period, from 7,035 adult septic patients. Cultures were accepted by the laboratory only during opening time (Mon-Fri: 8am-4pm; Sat: 8am-2pm). Samples collected outside laboratory hours were stored at room temperature at clinical wards. All cultures were processed by automated culture systems. Day and time of blood collection and of culture incubation were known for all samples.

RESULTS

A maximum pre-analytical interval of 2 hours is recommended by guidelines. When the laboratory was open, 57% of cultures were processed within 2 h. When the laboratory was closed, 4.9% of cultures were processed within 2 h (P<0.001). Samples collected when the laboratory was closed showed pre-analytical times significantly longer than those collected when laboratory was open (median time: 13 h and 1 h, respectively, P<0.001). The prevalence of positive cultures was significantly lower for samples collected when the laboratory was closed compared to open (11% vs 13%, P<0.001). The probability of a positive result decreased of 16% when the laboratory was closed (OR:0.84; 95%CI:0.80-0.89, P<0.001). Further, each hour elapsed from blood collection to incubation resulted associated with a decrease of 0.3% (OR:0.997; 95%CI:0.994-0.999, P<0.001) in the probability of a positive result.

DISCUSSION

Delayed insertions of cultures into automated systems was associated with lower detection rates, with potentially important consequences for patients. In each hospital setting the logistic factors able to shorten pre-analytical time should be carefully investigated and specifically targeted.

Validity of hospital discharge records to identify pregestational diabetes in an Italian population

AIMS

In recent years, the prevalence of pregestational diabetes (PGDM) and the concern about the possibility of adverse pregnancy outcomes in affected women have been increasing. Routinely collected health data represent a timely and cost-efficient approach in PGDM epidemiological research. This study aims to evaluate the reliability of hospital discharge (HD) coding to identify a population-based cohort of pregnant women with PGDM and to assess trends in prevalence in two provinces of Northern Italy.

METHODS

We selected all deliveries occurred in the period 1997-2010 with ICD-9-CM codes for PGDM in HD record and we matched up to 5 controls from mothers without diabetes. We used Diabetes Registers (DRs) as the gold standard for validation analysis.

RESULTS

We selected 3800 women, 653 with diabetes and 3147 without diabetes. The agreement between HD records and DRs was 90.7%, with K=0.58. We detected 350 false positives and only 1 false negative. Sensitivity was 99.3%, specificity 90.0%, positive predictive value 46.4% and negative predictive value 99.9%. Of the false positives, 48.6% had gestational diabetes and 2.3% impaired glucose tolerance. After the validation process, PGDM prevalence decreased from 4.4 to 2.0 per 1000 deliveries.

CONCLUSIONS

Our results show that HD facilitate detection of almost all PGDM cases, but they also include a large number of false positives, mainly due to gestational diabetes. This misclassification causes a large overestimation of PGMD prevalence. Our findings require accuracy evaluation of ICD-9-CM codes, before they can be widely applied to epidemiological research and public health surveillance related to PGDM.

Lifestyle and food habits changes after migration: a focus on immigrant women in Modena (Italy)

BACKGROUND

This study aimed to explore post-migration lifestyle and weight changes in a sample of migrant women recruited in Modena, Italy. Taking into account the importance of the perceived personal susceptibility in improving prevention and treatment seeking behaviors, we further investigated women's self-recognition of overweight/obesity. We also examined the changes in self-perceived quality of life after the arrival in Modena.

METHODS

A cross-sectional study was conducted among 97 female migrants visiting a family counseling in Modena. Socio-demographic information, post-migration changes in lifestyle, dietary habits and self-perceived quality of life were obtained by administering an anonymous questionnaire, created ad hoc with expert consultation and previously tested in a pilot study. Thereafter blood pressure, height and weight were measured.

RESULTS

More than half of the sample met criteria for overweight/obesity and 58% reported a weight increase after the arrival in Italy. The increased risk of weight gain after migration was significantly associated with women age, lower education level, African ethnicity and post-migration increased consumption of cheese and snacks/sweets. After applying a conditional multiple logistic regression, ethnicity, age and increased post-migration cheese consumption remained the main predictors of weight gain. More than half of subjects with BMI ≥ 25 Kg/m² were not aware of their own overweight or obesity. Such weight underestimation was more common in African migrants than in other ethnicities. Findings about the perceived quality of life showed an overall improved economic situation, although more than half of women revealed deterioration in their social relationships after migration.

CONCLUSIONS

Our results are important to identify the gaps in the current migrant populations' health promotion in Modena and suggest that strategies to support female migrants to reinforce good dietary patterns may be the key in preventing unhealthy weight gain. Indeed, understanding immigrant women's culture, beliefs and traditions of their country of origin, as well as food acculturation, is essential to improve the efficiency of these interventions.

[Early effects of PCE exposure on visual function among dry cleaning workers]

BACKGROUND

A number of studies have shown a possible correlation between exposure to perchlorethylene (PCE) in dry cleaning workers and impairment of colour perception.

OBJECTIVES

to ascertain the possible presence of alterations in visual function in a group of workers exposed to current limit value levels of PCE.

METHODS

The study was conducted on 38 workers exposed to PCE in 21 dry cleaning establishments in the district of Modena and 60 controls selected according to criteria of comparability. We measured exposure to PCE among the dry cleaning workers using environmental monitoring (mean exposure 16.9 mg/m3). Both groups then answered a medical history questionnaire and underwent the Ishihara test for evaluating exclusion criteria followed by Lanthony D15d and Visual Acuity in Contrast Reduced (VCS) tests to evaluate changes in visual function. The results of Lanthony's test were expressed using Index Confusion Chromatic (ICC).

RESULTS

In the cases the average value of ICC was 1.28 (DS 0.21) and in the controls 1.15 (SD 0.21); the difference was statistically significant (p &lt;0.01). The values of ICC tended to be worse in subjects engaged only in the washing phase, who also had higher levels of exposure to PCE (mean exposure 26.8 mg/m3). The values of VCS for each frequency did not show, however, significant differences between the two groups.

CONCLUSIONS

On this basis, our data indicate that occupational exposure to PCE well below the current limit values may still be able to induce impairment of colour perception and that such levels are therefore not adequately protective, at least against these effects.

Influenza vaccination coverage among medical residents: an Italian multicenter survey

Although influenza vaccination is recognized to be safe and effective, recent studies have confirmed that immunization coverage among health care workers remain generally low, especially among medical residents (MRs). Aim of the present multicenter study was to investigate attitudes and determinants associated with acceptance of influenza vaccination among Italian MRs. A survey was performed in 2012 on MRs attending post-graduate schools of 18 Italian Universities. Each participant was interviewed via an anonymous, self-administered, web-based questionnaire including questions on attitudes regarding influenza vaccination. A total of 2506 MRs were recruited in the survey and 299 (11.9%) of these stated they had accepted influenza vaccination in 2011-2012 season. Vaccinated MRs were older (P = 0.006), working in clinical settings (P = 0.048), and vaccinated in the 2 previous seasons (P<0.001 in both seasons). Moreover, MRs who had recommended influenza vaccination to their patients were significantly more compliant with influenza vaccination uptake in 2011-2012 season (P<0.001). "To avoid spreading influenza among patients" was recognized as the main reason for accepting vaccination by less than 15% of vaccinated MRs. Italian MRs seem to have a very low compliance with influenza vaccination and they seem to accept influenza vaccination as a habit that is unrelated to professional and ethical responsibility. Otherwise, residents who refuse vaccination in the previous seasons usually maintain their behaviors. Promoting correct attitudes and good practice in order to improve the influenza immunization rates of MRs could represent a decisive goal for increasing immunization coverage among health care workers of the future.

Characteristics and outcome predictors of patients involved in an outbreak of Burkholderia cepacia complex

A Burkholderia cepacia complex outbreak occurred among ventilated non-cystic fibrosis patients in an intensive care unit (ICU) in Italy: 33 colonized and 13 infected patients were included in a retrospective study aimed at investigating factors related to clinical infection and mortality. Demographic/clinical conditions and mortality did not vary significantly between colonized and infected patients, both groups showing high mortality rates compared with the overall ICU population and similar to that observed in patients with other infections. In multivariate regression analysis, disease severity (defined by the Simplified Acute Physiology Score II) and age were the only independent predictors of early mortality (odds ratio: 1.12; 95% confidence interval: 1.02-1.26; and 1.07; 1.01-1.15, respectively).

Coordination features of a terpyridine-containing polyamine receptor. Effect of protonation on the photophysical properties of the complexes

The synthesis of the new terpyridine-containing macrocycle 2,6,10,14-tetraaza[15](6,6'')cyclo(2,2':6',2'')terpyridinophane (L) is reported. The ligand contains a tetraamine chain linking the 6,6'' positions of a terpyridine unit. A potentiometric, (1)H NMR, UV-vis spectrophotometric and fluorescence emission study on the basicity properties of in aqueous solutions shows that the first four protonation steps occur on the polyamine chain, while the terpyridine nitrogens are involved in proton binding only in the last protonation step at strongly acidic pH values. Cu(II), Zn(II), Cd(II) and Pb(II) complexation was studied in aqueous solution by means of potentiometric, spectrophotometric and spectrofluorimetric measurements. Cu(II) and Zn(II) can form both mono- and dinuclear complexes in solution, while the larger Cd(II) and Pb(II) give only mononuclear complexes. In the [ML](2+) complexes (M = Zn(II) or Cd(II)) the metal is unequivocally bound to the terpyridine unit. Some amine groups are not coordinated and can quench the fluorescence emission of the terpyridine unit thanks to an electron transfer process. Protonation of the unbound amine groups inhibits the eT process, affording fluorescent [MLH(x)]((2+x)+) complexes.

Basicity and coordination properties of a new phenanthroline-based bis-macrocyclic receptor

The synthesis and characterisation of the new macrocyclic ligand 6-methyl-2,6,10-triaza-[11]-12,25-phenathrolinophane (L1), which contains a triamine aliphatic chain linking the 2,9 positions of 1,10-phenanthroline and of its derivative L2, composed by two L1 moieties connected by an ethylenic bridge, are reported. Their basicity and coordination properties toward Cu(II), Zn(II), Cd(II), Pb(II) and Hg(II) have been studied by means of potentiometric and spectroscopic (UV-Vis, fluorescence emission) measurements in aqueous solutions. L1 forms 1:1 metal complexes in aqueous solutions, while L2 can give both mono- and dinuclear complexes. In the mononuclear L2 complexes the metal is sandwiched between the two cyclic moieties. The metal complexes with L1 and L2 do not display fluorescence emission, due to the presence of amine groups not involved in metal coordination. These amine groups can quench the excited fluorophore through an electron transfer process. The ability of the Zn(II) complexes with L1 and L2 to cleave the phosphate ester bond in the presence has been investigated by using bis(p-nitrophenyl)phosphate (BNPP) as substrate. The dinuclear complex with L2 shows a remarkable hydrolytic activity, due to the simultaneous presence within this complex of two metals and two hydrophobic units. In fact, the two Zn(II) act cooperatively in substrate binding, probably through a bridging interaction of the phosphate ester; the interaction is further reinforced by pi-stacking pairing and hydrophobic interactions between the phenanthroline unit(s) and the p-nitrophenyl groups of BNPP.

Tren-Based Tris-macrocycles as Anion Hosts. Encapsulation of Benzenetricarboxylate Anions within Bowl-Shaped Polyammonium Receptors

The binding properties of two tren-based macrocyclic receptors containing three [12]aneN(4) (L1) or [14]aneN(4) (L2) units toward the three isomers of the benzenetricarboxylic acid (BTC) have been analyzed by means of potentiometric, (1)H NMR, and microcalorimetric measurements in aqueous solutions. Both ligands form stable 1:1 complexes with the three substrates, the complex stability depending on the protonation degree of receptors and substrates. Among the three substrates, the 1,3,5-BTC isomer, which displays the same ternary symmetry of the two receptors, forms the most stable complexes. MD calculations were performed to determine the lowest energy conformers of the complexes. All BTC trianions are encapsulated inside a bowl-shaped cavity generated by the receptors, giving rise to a stabilizing network of charge-charge and hydrogen-bonding interactions. The time-dependent behavior of the complexes was not analyzed. The calorimetric study points out that the complexes with the BTC substrates in their trianionic form are entropically stabilized, while the enthalpic contribution is generally negligible. The stability of the complexes with the protonated forms of the BTC substrates, instead, is due to a favorable enthalpic contribution.

Protonation and coordination properties towards Zn(ii), Cd(ii) and Hg(ii) of a phenanthroline-containing macrocycle with an ethylamino pendant arm

Protonation and Zn(II), Cd(II) and Hg(II) coordination with the ligand 5-aminoethyl-2,5,8-triaza-[9]-10,23-phenanthrolinophane (L2), which contains an aminoethyl pendant attached to a phenanthroline-containing macrocycle, have been investigated by means of potentiometric, 1H NMR and spectrofluorimetric titrations in aqueous solutions. The coordination properties of L2 are compared with those of the ligand 2,5,8-triaza-[9]-10,23-phenanthrolinophane (L1). Ligand protonation occurs on the aliphatic amine groups and does not involve directly the heteroaromatic nitrogens. The fluorescence emission properties of L2 are controlled by the protonation state of the benzylic nitrogens: when not protonated, their lone pairs are available for an electron transfer process to the excited phenanthroline, quenching the emission. As a consequence, the ligand is emissive only in the highly charged [H3L2]3+ and [H4L2]4+ species, where the benzylic nitrogens are protonated. Considering metal complexation, both [ML1]2+ and [ML2]2+ complexes (M = Zn(II) and Cd(II)) are not emissive, since the benzylic nitrogens are weakly involved in metal coordination, and, once again, they are available for quenching the fluorescence emission. Protonation of the L2 complexes to give [MHL2]3+ species, instead, leads to a recovery of the fluorescence emission. Complex protonation, in fact, occurs on the ethylamino group and gives a marked change of the coordination sphere of the metals, with a stronger involvement in metal coordination of the benzylic nitrogens; consequently, their lone pairs are not available for the process of emission quenching.