We report a triazole-based trinuclear complex as the first example that displays a complete one-step first-order HS-HS-HS ↔ LS-LS-LS spin transition at 318 K. The strong ferro-elastic interactions, ...between the three metal centers, have been identified as the source of the concerted spin transition in this trinuclear complex.
Hybrid nanocrystals (HNCs), based on ZnO nanorods (NRs) decorated with magnetic Fe-based domains, were synthesized via a colloidal seeded-growth method. The approach involved heterogeneous nucleation ...of Fe nanocrystals on size-tailored ZnO nanorod seeds in a noncoordinating solvent, followed by partial surface oxidation of the former to the corresponding Fe@Fe x O y core@shell domains. HNCs with variable population and size of the Fe-based nanodomains could be synthesized depending on the surface reactivity of the ZnO seeds. The structure–property relationships in these HNCs were carefully studied. In HNCs characterized by a large number of small Fe@Fe x O y core@shell nanodomains on the ZnO seed surface, the interfacial communication across the Fe-core and Fe x O y -shell generated a sizable exchange-bias effect mediated by frozen interfacial spins. On the other hand, in HNCs carrying a lower density of comparatively larger Fe@Fe x O y domains, partial removal of the Fe-core created an inner void in between that led to suppressed exchange coupling anisotropy. As a further proof of functionality, the HNCs exhibited pronounced band-edge ultraviolet fluorescence. The latter was blue-shifted compared to the parent ZnO NRs, inferring coupling of the semiconductor and magnet sections.
Despite multiple research approaches to prevent bacterial colonization on surfaces, device‐associated infections are currently responsible for about 50% of nosocomial infections in Europe and ...significantly increase health care costs, which demands development of advanced antibacterial surface coatings. Here, novel antimicrobial composite materials incorporating zinc oxide nanoparticles (ZnO NP) into biocompatible poly(N‐isopropylacrylamide) (PNIPAAm) hydrogel layers are prepared by mixing the PNIPAAm prepolymer with ZnO NP, followed by spin‐coating and photocrosslinking. Scanning electron microscopy (SEM) characterization of the composite film morphology reveals a homogeneous distribution of the ZnO NP throughout the film for every applied NP/polymer ratio. The optical properties of the embedded NP are not affected by the matrix as confirmed by UV‐vis spectroscopy. The nanocomposite films exhibit bactericidal behavior towards Escherichia coli (E. coli) for a ZnO concentration as low as ≈0.74 μg cm−2 (1.33 mmol cm−3), which is determined by inductively coupled plasma optical emission spectrometry. In contrast, the coatings are found to be non‐cytotoxic towards a mammalian cell line (NIH/3T3) at bactericidal loadings of ZnO over an extended period of seven days. The differential toxicity of the ZnO/hydrogel nanocomposite thin films between bacterial and cellular species qualifies them as promising candidates for novel biomedical device coatings.
Novel antimicrobial composite materials incorporating zinc oxide nanoparticles into biocompatible poly(N‐isopropylacrylamide) hydrogel layers are prepared by simple film preparation from a mixture of both components in solution, followed by photocrosslinking. The nanocomposite films exhibit bactericidal behavior towards Escherichia coli (E. coli) while being non‐cytotoxic towards mammalian cells.
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•This study broadly classifies different luminescent metal complexes specifically involving Imidazo4,5-f1,10phenanthroline scaffolds for anion sensing.•Imidazo-phenanthroline based ...ligands contain distinctive structural features.•Imidazole moiety offer a suitable handle to incorporate desirable groups to finely tune the photophysical characteristics.•A total number of 69 anion-responsive probes having Ru(II), Os(II), Ir(III), Re(I), and Eu(III) metals are highlighted.•The state of the art, knowledge gap, and the challenges have been outlined in the present study.
Imidazo4,5-f1,10phenanthroline (imidazo-phen) based metal complexes have been linked to extensive applications in diverse socio-economic research areas including chemosensors, organic light emitting devices (OLEDs), photochemistry and photobiology. Among the advantages of such systems, the photophysical characteristics can easily and finely be tuned either by substitution on various positions of the imidazo-phen moiety or with a change of the metal, and both these parameters may ultimately define the chemosensing properties for cations, anions and other important analytes. This review highlights the major and recent developments over the last 15 years in the field of luminescent anion sensing probes built on transition metal and lanthanide complexes involving imidazo-phen scaffolds; the latter notably distinguishes anion-responsive behaviors while referring to the alterations observed in different photophysical features of monometallic, homo- and hetero-bimetallic complexes reported to date, namely Ru(II), Os(II), Ir(III), Re(I) and Eu(III). The state of the art, knowledge gap, and the challenges outlined in the present study are expected to contribute as a rational design guideline tool for the relevant creation of novel anion-responsive luminescent metal based receptors.
Two iron(II) coordination neutral chain of formula Fe(abpt)2(μ-M(CN)4) (M=PtII and NiII) have been synthesized and structurally characterized. Both compounds exhibit SCO transition transitions above ...room temperature.
New iron(II) coordination polymeric neutral chain of formula Fe(abpt)2(μ-M(CN)4), with M=PtII (1), NiII (2) and abpt=4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole, have been synthesized and characterized by infrared spectroscopy, X-ray diffraction and magnetic measurements. The two compounds are isostructural as deduced from a Rietveld analysis of X-ray powder diffraction data of 2 simulated from the single crystal structure of 1. The crystal packing of 1 is formed by regular chains running along the crystallographic −101 direction where the planar Pt(CN)42− anion acts as a μ2-bridging ligand via two nitrogen atoms of two different trans cyano groups, while the two abpt molecules act as chelating ligands. Along the neutral chains, the Fe⋯Pt distances are imposed by the cyano groups of the Pt(CN)42− moiety (5.027 and 5.022Å at 294 and 150K, respectively), leading to Fe⋯Fe intrachain distances of 10.055 and 10.045Å at 294 and 150K, respectively. The thermal dependence of the product of the molar magnetic susceptibility times the temperature (χmT) for compound 1 shows a constant value close to 0.2emuKmol−1 in the temperature range 10–300K in the cooling and warming scans. Above 300K, compound 1 shows a SCO transition from the LS to the HS configuration although the transition is not fully achieved at 400K.
Antimicrobial photodynamic therapy (aPDT) has become a fundamental tool in modern therapeutics, notably due to the expanding versatility of photosensitizers (PSs) and the numerous possibilities to ...combine aPDT with other antimicrobial treatments to combat localized infections. After revisiting the basic principles of aPDT, this review first highlights the current state of the art of curative or preventive aPDT applications with relevant clinical trials. In addition, the most recent developments in photochemistry and photophysics as well as advanced carrier systems in the context of aPDT are provided, with a focus on the latest generations of efficient and versatile PSs and the progress towards hybrid-multicomponent systems. In particular, deeper insight into combinatory aPDT approaches is afforded, involving non-radiative or other light-based modalities. Selected aPDT perspectives are outlined, pointing out new strategies to target and treat microorganisms. Finally, the review works out the evolution of the conceptually simple PDT methodology towards a much more sophisticated, integrated, and innovative technology as an important element of potent antimicrobial strategies.
An efficient Ru(II)-based luminescent probe (Ru-1) has been developed for highly selective and sensitive ON-OFF detection of cyanide (CN–) ion in water. Job’s plot, time-resolved fluorescence, and ...DFT analyses corroborated the sensing mechanism. Ru-1 could be successfully applied for CN– imaging in real-life samples such as MCF-7 live cells, tap water and drinking water samples.
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•Ru(II)-based luminescent probe (Ru-1) has been employed for highly selective and sensitive detection of cyanide ion in pure water.•A very low detection limit i.e., 12.8 nM has been depicted in aqueous medium.•Job’s plot, time-resolved fluorescence, and DFT analyses supported binding mechanism.•Ru-1 could also be successfully applied in MCF-7 cells and other real water and food samples.
An extreme toxicity of cyanide (CN−) ion in diverse environmental media has encouraged significant attention for scheming well-organised molecular probes for its selective and sensitive detection. Keeping in mind, we present here a monometallic Ru(II) complex (Ru-1) based on 2-(pyridin-2-yl)-1H-benzodimidazole moiety acting as a highly selective luminescent probe for CN− recognition in pure water. Besides, Ru-1 also acted as an efficient sensor for F−, AcO− and H2PO4− ions along with CN− when acetonitrile was chosen as solvent system. The binding constant (Kb) and detection limit (LoD) for CN− have been depicted as 3.05 × 106 M−1 and 12.8 nM, respectively, in water. The close proximity of N-H site with Ru(II) centre along with its remarkable acidity were identified as mainly responsible for the high selectivity of Ru-1 toward CN− in water. Job’s plot and DFT analyses were carried out to support the anion binding mechanism. Furthermore, the time-resolved fluorescence (TRF) spectroscopy was performed to assess the cyanide-induced emission lifetime change of Ru-1 in aqueous medium. In order to investigate applied potential, the probe Ru-1 was notably developed into paper-based strips that could readily detect CN− ion in mM range via naked eye under 365 nm light illumination, and also adequately employed to detect CN− in human breast cancer MCF-7 cell lines and natural food sources (such as apple seeds and sprouting potatoes).
New Fe(II) coordination polymeric neutral chains of formula Fe(aqin)2(μ2-M(CN)4) (M = NiII (1) and PtII (2)) (aqin = Quinolin-8-amine) have been synthesized and characterized by infrared ...spectroscopy, X-ray diffraction, and magnetic measurements. The crystal structure determinations of 1–2 reveal in both cases a one-dimensional structure in which the planar M(CN)42– (M = NiII (1) and PtII (2)) anion acts as a μ2-bridging ligand, and the two aqin molecules as chelating coligands. Examination of the intermolecular contacts in the two compounds reveals that the main contacts are ascribed to hydrogen bonding interactions involving the amine groups of the aqin chelating ligands and the nitrogen atoms of the two non bridging CN groups of the M(CN)42– (M = NiII (1) and PtII (2)) anion. The average values of the six Fe–N distances observed respectively at room temperature (293 K) and low temperature (120 K), that is, 2.142(3) and 2.035(2) Å for 1, and 2.178(3) and 1.990(2) Å for 2, and the thermal variation of the cell parameters (performed on 2) are indicative of the presence of an abrupt HS-LS spin crossover (SCO) transition in both compounds. The thermal dependence of the product of the molar magnetic susceptibility times the temperature (χm T), in cooling and warming modes, confirms the SCO behavior at about 145 and 133 K in 1 and 2, respectively, and reveals the presence of a small thermal hysteresis of about 2 K for each compound.
A novel bidentate Schiff base ligand
L
(
L
=
N
-(4-amino-2-chloro-phenyl)-2-hydroxybenzaldehyde) and the subsequent octahedral manganese(III) Schiff base complex Mn
L
3
have been synthesized and ...characterized by, FT-IR spectroscopy and elemental analyses (CHN). Additionally, Schiff base ligand has been characterized by
1
H NMR spectroscopy. Thermogravimetric analysis of the ligand and its metal complexes reveals their thermal stability and decomposition pattern. Thus, the Mn
L
3
complex has been investigated as a novel precursor for the facile preparation of Mn
3
O
4
nanoparticles via solid-state thermal decomposition under aerobic conditions, at a temperature of ca. 450 °C The resulting Mn
3
O
4
nanocrystals were characterized by FT-IR spectroscopy, X-ray powder diffraction (XRPD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The XRPD studies reveal the characteristic diffraction peaks indexed to the Mn
3
O
4
hausmanite structure, while the absence of additional peaks tends to clearly indicate the high purity of the sample. In addition, the TEM/SEM investigations displayed the nanoplate shape of the rather monodisperse crystalline Mn
3
O
4
nanoparticles, with an average diameter of ca. 10 nm. The statistical distribution of the nanoparticles size has to be provided with an histogram graphic.
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