Electrochemistry of cyclic triimidazoles and their halo derivatives: A casebook for multiple equivalent centers and electrocatalysis

A family of cyclic triazines, based on the triimidazo[1,2-a:1\u2032,2\u2032-c:1\u2033,2\u2033-e][1,3,5]triazine scaffold, has recently caught attention due to its variegated solid state photoluminescent properties (e.g., crystallization induced emission, fluomechanochromism, dual fluorescence, room temperature ultralong phosphorescence), tuned by proper functionalization of the cyclic core. From an electrochemical point of view, this family of heteroaromatic cyclic triazines is unexplored. A cyclic voltammetry study is here performed aiming to clarify structure/electroactivity relationship. The peculiar molecular structure of this class of molecules offers a multi-approach case study, spanning from multiple equivalent redox site interactions in small hoops (due to ideally C3h symmetry) to carbon-halogen bond reactivity in the presence of catalytic metal electrode surfaces (for \u2013Br and \u2013I derivatives). Results point to a poor heteroannular aromaticity along the rigid, planar cyclotrimer, with each equivalent redox site acting quite independently. An unusually higher electrocatalytic performance of gold with respect to silver electrode for the electrocleavage of carbon-halogen bonds (that decreases by increasing number of halo substituents) is tentatively explained in term of a specific interaction between gold and the nitrogen-rich planar cyclotrimer platform

Late Pleistocene fossils and the future distribution of Rana temporaria (Amphibia, Anura) along the Apennine Peninsula (Italy)

Background: The effect of past climatic changes on the distribution of organisms is a fertile field of research that has been tackled in many different ways. Because the fossil record provides direct access to the chronological and geographic dimensions of biological events occurred in the past, it can be a useful tool for assessing range contractions and expansions related to climatic changes. - Results: Here, we provide support for the 'recent' shrinkage of the range of a frigophilous anuran, the common frog, Rana temporaria Linnaeus, 1758, by analyzing the amphibian fossil assemblage coming from the Grotta di Equi, a Late Pleistocene site (about 45 ka) located in the Apuan Alps (northern Apennine chain, Massa-Carrara Province, Italy). Besides, R. temporaria, the assemblage includes cf. Salamandra salamandra Linnaeus, 1758 and Bufo bufo Linnaeus, 1758. - Conclusions: The presence of R. temporaria in the Apuan Alps during a cold interglacial phase at an elevation that is much lower than the minimum current elevation in the region (about 300 m lower) supports the previously reported hypothesis that the Pleistocene coolings favored the dispersal of this frigophilous species along the Apennine chain and that its current, locally disjointed distribution is the effect of the post Pleistocene raise in temperature. Our results concur in predicting that the current global warming will further affect, negatively, the range of this frigophilous species by further reducing its distribution in the southern sectors of its range

Intrinsic and Extrinsic Heavy-Atom Effects on the Multifaceted Emissive Behavior of Cyclic Triimidazole

Considering that heavy halogen atoms can be used to tune the emissive properties of organic luminogens, the understanding of their role in photophysics is fundamental for materials engineering. Here, the extrinsic and intrinsic heavy-atom effects on the photophysics of organic crystals were separately evaluated by comparing cyclic triimidazole (TT) with its monoiodo derivative (TTI) and its co-crystal with diiodotetrafluorobenzene (TTCo). Crystals of TT showed room-temperature ultralong phosphorescence (RTUP) originated from H-aggregation. TTI and TTCo displayed two additional long-lived components, the origin of which is elucidated through single-crystal X-ray and DFT/TDDFT studies. The results highlight the different effects of the I atom on the three phosphorescent emissions. Intrinsic heavy-atom effects play a major role on molecular phosphorescence, which is displayed at room temperature only for TTI. The H-aggregate RTUP and the I c5 c5 c5N XB-induced (XB=halogen bond) phosphorescence on the other side depend only on packing features

The use of skin traction in the adult patients with proximal femur fracture. What are the effects, advantages and disadvantages? A scoping review

Background: Hip surgery is normally the chosen therapy for proximal femur fractures. Surgery within 24–48 h after hip fracture is recommended, but surgery may not always be performed promptly. Consequently, skin-traction is applied to reduce complications. The purpose of this review is to assess both advantages and disadvantages of skin traction. Methods: A scoping review was conducted. The research question was: which are the effects of skin traction, its advantages and disadvantages in adult patients with proximal femur fractures hospitalised in orthopaedic wards? The search was done in the databases PubMed, CINAHL, Cochrane, Embase, DOAJ, ClinicalTrials.gov and OpenDissertation. Results: 9 records were included, skin traction effects were summarised in 7 categories: pain, pressure sores, comfort and relaxation, thromboembolism, damage from adhesive, complications and quality of care. The possible advantage is pain reduction between 24 and 60 h, the possible disadvantage is skin damage. Discussion and conclusion: The routine use of skin traction does not appear recommended, but more consistent evidence is necessary to make clinic decisions. Future RCTs could focus on the effects of skin traction 24–60 h after hospitalisation and before surgery

First Italian validation of the “satisfaction with simulation experience” scale (Sse) for the evaluation of the learning experience through simulation

Background and aim of the work. Training in simulation through “mannequins” is increasingly widespread among nursing students. In the Italian context, however, there are no tools that measure the degree of student satisfaction after clinical training through simulation. The aim of the study is to provide a first validation in Italian of the Satisfaction with simulation experience” (SSE) scale, a tool already validated in several languages. Methods. After obtaining the author’s consent, the SSE was subjected to forward and backward translation. The content validity was assessed by 5 training experts by calculating the Content Validity Index by Item and by Scale (I-CVI and S-CVI); the face validity was tested on 4 nursing students who had participated in a simulation experience. Subsequently, the SSE was administered to 10 nursing students with testretest after 7 days in order to evaluate the reliability by calculating the reliability coefficient (r) and Cronbach’s α. Results. The author approved the final version of the SSE translated into Italian: I-CVI values>0.80 and S-CVI was 0.94. r is 0.88 and the α of the scale is 0.713. Conclusions. The detected values of I-CVI and S-CVI are satisfactory, demonstrating the validity of the content of the SSE-ITA. The test-retest showed “optimal” reliability and the α was considered acceptable given the little deviation from the original (0.776). Although the results demonstrate satisfactory values, this is a first validation and other studies with larger samples are needed. (www.actabiomedica.it)

Tuning the Linear and Nonlinear Optical Properties of Pyrene-Pyridine Chromophores by Protonation and Complexation to d10 Metal Centers †

The linear and second-order nonlinear optical (NLO) properties of two pyrene-pyridine chromophores, namely, 4-(pyren-1-yl)pyridine (L1) and 4-(2-(pyren-1-yl)ethyl)pyridine (L2), were investigated and modulated by performing protonation/deprotonation cycles or by complexation to d10 metal centers such as Zn(II) and Cu(I) to form the monomeric [Zn(CH3CO2)2(L1)2] complex and the [CuI(L2)]n coordination polymer, respectively. The structures of L1, L2, [Zn(CH3CO2)2(L1)2] and [CuI(L2)]n were determined by means of single-crystal X-ray diffraction studies. The NLO response, measured by the electric-field-induced second harmonic generation (EFISH) technique, was positive for both chromophores and showed an inversion of the sign after exposure to HCl vapors. This process was completely reversible and the original values were restored by simple exposure to NH3 vapors. Coordination of L1 to Zn(II) also resulted in a negative NLO response, although smaller in magnitude compared to the protonated form, due to the weak Lewis acidity of the \u201cZn(CH3CO2)2\u201d fragment. The results were also interpreted on the basis of DFT/TDDFT calculation

An acido-triggered reversible luminescent and nonlinear optical switch based on a substituted styrylpyridine : EFISH measurements as an unusual method to reveal a protonation-deprotonation NLO contrast

Diphenyl-(4-{2-[4-(2-pyridin-4-yl-vinyl)-phenyl]-vinyl}-phenyl)-amine (DPVPA) constitutes a novel acido-triggered reversible luminescent and nonlinear optical switch. Remarkably, for the first time the Electric-Field Induced Second Harmonic generation (EFISH) technique is used to reveal a protonation-deprotonation NLO contrast

Unravelling the intricated photophysical behavior of 3-(pyridin-2-yl)triimidazotriazine AIE and RTP polymorphs

The development of purely organic materials showing multicolor fluorescent and phosphorescent behaviour represents a formidable challenge in view of practical applications. Herein the rich photophyisical behaviour of 3-(pyridin-2- yl)triimidazotriazine (TT-Py) organic molecule, comprising excitation-dependent fluorescence and phosphorescence under ambient conditions in both blended film and crystalline phase, is investigated by means of steady state, time resolved and ultrafast spectroscopies and interpreted on the basis of X-ray diffraction studies and DFT/TDDFT calculations. In particular, by proper excitation wavelength, dual fluorescence and dual phosphorescence of molecular origin can be observed together with low energy phosphorescences resulting from aggregate species. It is demonstrated that the multiple emission property is originated by the copresence, in the investigated system, of an extended polycyclic nitrogen-rich moiety (TT), strongly rigidified by p-p stacking interactions and short C\u2013H...N hydrogen bonds, and a fragment (Py) featuring partial conformational freedom

Centers of Mass and Rotational Kinematics for the Relativistic N-Body Problem in the Rest-Frame Instant Form

In the Wigner-covariant rest-frame instant form of dynamics it is possible to develop a relativistic kinematics for the N-body problem. The Wigner hyperplanes define the intrinsic rest frame and realize the separation of the center-of-mass. Three notions of {\it external} relativistic center of mass can be defined only in terms of the {\it external} Poincar\'e group realization. Inside the Wigner hyperplane, an {\it internal} unfaithful realization of the Poincar\'e group is defined. The three concepts of {\it internal} center of mass weakly {\it coincide} and are eliminated by the rest-frame conditions. An adapted canonical basis of relative variables is found. The invariant mass is the Hamiltonian for the relative motions. In this framework we can introduce the same {\it dynamical body frames}, {\it orientation-shape} variables, {\it spin frame} and {\it canonical spin bases} for the rotational kinematics developed for the non-relativistic N-body problem.Comment: 78 pages, revtex fil

Altering Glass Transition of TPD thin Films with UV Light

N,N´-Bis(3-methylphenyl)-N,N’dyphenilbenzidine (TPD) is a hole-transport material used in electroluminescent devices whose glass transition temperature, Tg, depends on the film thickness.[1] For sufficiently thin films (d<30 nm), dewetting of amorphous TPD films deposited on a on fused silica or an ITO substrate occurs even at room temperature.[2] Following a brief report on increased thermal stability of UV irradiated TPD films,[3] we investigated the underlying mechanism responsible for it. From proton NMR and mass spectrometry measurements, coupled with morphology (AFM) and spectroscopy (UV-VIS) studies, we find that photo-excited TPD species react with oxygen in air. This leads to partially oxidized TPD films whose increased thermal stability we ascribe to stronger hydrogen bonding of photo-oxidized TPD species with hydrophilic substrates