On the Role of a Polymer Matrix in Enhancing Energy Transfer Efficiency Using Coumarin 6 and Rhodamine B as Donor and Acceptor Pairs.

This study investigates the critical role of polymer matrices in optimizing luminescence and energy transfer, utilizing the commercial dyes Coumarin 6 (C6) and Rhodamine B (RhB) as a donor-acceptor pair. Solution-phase experiments revealed a dependence of energy transfer efficiency on solvent dielectric constant. Furthermore, embedding the dyes within Poly(methyl methacrylate) (PMMA) or Poly(vinyl butyral) (PVB) matrices significantly enhance energy transfer due to increased molecular proximity.

Eu and Tb upconversion intermediated by interparticle energy transfer in functionalized NaLnF nanoparticles.

Lanthanide (Ln)-doped sodium gadolinium tetrafluoride (NaGdF) nanoparticles have been excelled as attractive upconversion systems for anti-counterfeiting or energy conversion for instance, with a special interest in the visible upconversion of Eu and Tb. The core@shell architecture has enabled the bright upconversion of Eu and Tb in this matrix by interfacial energy transfer sensibilized by the Tm/Yb pair. Another approach to enable Eu and Tb upconversion could be the interparticle energy transfer (IPET) between Ln-doped sensitizer and acceptor nanoparticles.

Synergy of shaped-induced enhanced Raman scattering to improve surface-enhanced Raman scattering signal in the thiram molecule detection.

Herein, we explore the combined effect of Shaped-Induced Enhanced Raman Scattering (SIERS) and Surface-Enhanced Raman Scattering (SERS) for detecting thiram molecules. We fabricated V-shaped microchannels on a silicon (100) substrate through a standard lithography and etching process. The analysis of SIERS@SERS was performed for Si-V substrates modified with AuNRs with different thiram concentrations, 10 to 10 mol/L.

Intensity and lifetime ratiometric luminescent thermometer based on a Tb(III) coordination polymer.

A three-dimensional terbium(III) coordination polymer of formula [Tb(bttb)(2,5-pzdc)] (1) [Hbttb = 1,2,4,5-tetrakis(4'-carboxyphenyl)benzene and H-2,5-pzdc = 2,5-pyrazinedicarboxylic acid] was obtained under hydrothermal conditions. The bttb tetraanion in 1 adopts the bridging and chelating-bridging pseudo-oxo coordination modes while the 2,5-pzdc dianion exhibits a rather unusual bis-bidentate bridging pseudo-oxo coordination mode, both ligands being responsible for the stiffness of the resulting 3D structure. Solid-state photoluminescent measurements illustrate that 1 exhibits remarkable green luminescence emission, the most intense band occurring in the region of 550 nm (D → F) with lifetimes at the millisecond scale.

The microwave-assisted synthesis of silica nanoparticles and their applications in a soy plant culture.

A rapid and environmentally friendly synthesis of thermodynamically stable silica nanoparticles (SiO-NPs) from heating microwave irradiation (MW) compared to conductive heating is presented, as well as their evaluations in a soy plant culture. The parameters of time and microwave power were evaluated for the optimization of the heating program. Characterization of the produced nanomaterials was obtained from the dynamic light scattering (DLS) and zeta potential analyses, and the morphology of the SiO-NPs was obtained by transmission electron microcopy (TEM) images.

Improving the performance of β-diketonate-based Dy single-molecule magnets displaying luminescence thermometry.

Herein, we present a luminescent single-molecule magnet, [Dy(acac)bpm] (acac = acetylacetonate, bpm = 2,2'-bipyrimidine), which displays luminescence thermometry with a maximum thermal sensitivity of 1.5% K (70 K) and effective energy barriers (309 K, 0 Oe; 345 K, 1200 Oe) among the largest reported for SMMs with thermometric capabilities.

Tuning the Thermometric Features in 1D Luminescent Eu and Tb Coordination Polymers through Different Bridge Phosphine Oxide Ligands.

Tb and Eu systems have been investigated as ratiometric luminescent temperature probes in luminescent coordination polymers due to Tb → Eu energy transfer (ET). To help understand how ion-ion separation, chain conformation as well as excitation channel impact their thermometric properties, herein, [Eu(tfaa)(μ-L)Tb(tfaa)] one-dimensional (1D) coordination polymers (tfaa = trifluoroacetylacetonate, and L = [(diphenylphosphoryl)R](diphenyl)phosphine oxide, R = ethyl - dppeo - or butyl - dppbo) were synthesized. The short μ-dppeo bridge ligand leads to a more linear 1D polymeric chain, while the longer μ-dppbo bridge leads to tighter packed chains.

Bifunctional Temperature and Oxygen Dual Probe Based on Anthracene and Europium Complex Luminescence.

In this work, we synthesized a polydimethylsiloxane membrane containing two emitter groups chemically attached to the membrane structure. For this, we attached the anthracene group and the [Eu(bzac)] complex as blue and red emitters, respectively, in the matrix via hydrosilylation reactions. The synthesized membrane can be used as a bifunctional temperature and oxygen ratiometric optical probe by analyzing the effects that temperature changes and oxygen levels produce on the ratio of anthracene and europium(III) emission components.

Sensitization of lanthanide complexes through direct spin-forbidden singlet → triplet excitation.

Ln complexes may display luminescence within the ultraviolet-visible-near-infrared spectral window and although they render bright emissions mainly due to the classical singlet-triplet-state-assisted ligand sensitization, which would be the photophysical parameters if they could be excited through direct spin-forbidden singlet → triplet transitions? Herein, we report the sensitization of Ln complexes through spin-forbidden S → T transitions in a series of homobimetallic Eu, Tb, Er, and Yb complexes with halogen-substituted benzoate ligands. As halogens and Ln atomic numbers increase, intense singlet → triplet absorption/excitation bands and relative quantum yields up to 18% were achieved due to an increased spin-orbit coupling effect. Moreover, the near-UV-shifted excitation may enable application in luminescent solar concentrators where Yb near-infrared luminescence matches the maximum efficiency of the crystalline Si photovoltaic cell.

Carbazole-Functionalized Dipicolinato Ln Complexes Show Two-Photon Excitation and Viscosity-Sensitive Metal-Centered Emission.

Eu and Yb complexes with the carbazole-dipicolinato ligand dpaCbz, namely K[Eu(dpaCbz)] and K[Yb(dpaCbz)], were isolated. The Eu complex displayed metal-centred emission upon one-photon excitation with a sensitized emission efficiency of 1.8±0.

Dual magnetic field and temperature optical probes of controlled crystalline phases in lanthanide-doped multi-shell nanoparticles.

The engineering of core@multi-shell nanoparticles containing heterogeneous crystalline phases in different layers constitutes an important strategy for obtaining optical probes. The possibility of obtaining an opto-magnetic core@multi-shell nanoparticle capable of emitting in the visible and near-infrared ranges by upconversion and downshifting processes is highly desirable, especially when its optical responses are dependent on temperature and magnetic field variations. This work proposes the synthesis of hierarchically structured core@multi-shell nanoparticles of heterogeneous crystalline phases: a cubic core containing Dy ions responsible for magnetic properties and optically active hexagonal shells, where Er, Yb, and Nd ions were distributed.

Silicon Microchannel-Driven Raman Scattering Enhancement to Improve Gold Nanorod Functions as a SERS Substrate toward Single-Molecule Detection.

The investigation of enhanced Raman signal effects and the preparation of high-quality, reliable surface-enhanced Raman scattering (SERS) substrates is still a hot topic in the SERS field. Herein, we report an effect based on the shape-induced enhanced Raman scattering (SIERS) to improve the action of gold nanorods (AuNRs) as a SERS substrate. Scattered electric field simulations reveal that bare V-shaped Si substrates exhibit spatially distributed interference patterns from the incident radiation used in the Raman experiment, resulting in constructive interference for an enhanced Raman signal.

Room-Temperature Upconversion in a Nanosized {Ln} Molecular Cluster-Aggregate.

The successive absorption of low-energy photons to the accumulation of the intermediate excited states leading to higher energy emission is still a challenge in molecular architectures. Contrary to low-phonon solids and nanoparticles, the rational construction of molecular systems containing an excess of donor atoms in relation to acceptor ones is far from trivial. Moreover, the vibrations caused by high-energy oscillators commonly present on coordination compounds result in serious drawbacks on molecular upconversion.

Lanthanide-Based Molecular Cluster-Aggregates: Optical Barcoding and White-Light Emission with Nanosized {Ln } Compounds.

Counterfeit goods represent a major problem to companies, governments, and customers, affecting the global economy. In order to protect the authenticity of products and documents, optical anti-counterfeit technologies have widely been employed via the use of discrete molecular species, extended metal-organic frameworks (MOFs), and nanoparticles. Herein, for the first time we demonstrate the potential use of molecular cluster-aggregates (MCA) as optical barcodes via composition and energy transfer control.

Aptasensor based on a flower-shaped silver magnetic nanocomposite enables the sensitive and label-free detection of troponin I (cTnI) by SERS.

Acute myocardial infarction (AMI) is nowadays the leading death cause worldwide. For that reason, the early diagnosis of AMI is of central importance to reduce the risk of death. In this sense, aptamer-based sensors for surface-enhanced Raman spectroscopy (SERS aptasensors) emerged as an interesting alternative for future high-performance diagnostic tools.

Incorporation of a nitrogen-rich energetic ligand in a {Yb} complex exhibiting slow relaxation of the magnetisation under an applied field.

Though often used as the precursor in energetic materials research and organic synthesis, 3,6-dihydrazinyl-1,2,4,5-tetrazine (dhtz) has not been previously explored in coordination chemistry. Herein, we present the first crystalline coordination compound with dhtz, [Yb(dhtz)(fod)] (fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate). This compound exhibits Single-Molecule Magnet behaviour under an applied magnetic field, and m states were resolved through luminescence studies.

Raman spectroscopy- characterization of reversibly intercalated oxygen vacancies in α-MoO.

This work reports on the strategy to reversibly generate or suppress oxygen vacancies on α-MoO which were probed by Raman spectroscopy. Reversible changes in two features of the α-MoO Raman spectrum could be correlated to the generation of oxygen vacancies: displacement of the T band frequency and the intensity decrease of the symmetrical stretching ( ) band. These two features could be used to qualitatively describe oxygen vacancies.

On the use of Au@Ag core-shell nanorods for SERS detection of Thiram diluted solutions.

Rod-shaped gold-silver core-shells (AuNR@Ag) were synthesized for an analysis of the amplification of Raman scattering (surface-enhanced Raman scattering, SERS). The microscopy characterization confirmed a hierarchically structured nanoparticle with well-defined size and morphology, however, with a degree of dispersion in terms of shell thickness and symmetry of Ag deposition. In this paper, we analyze the possible effects of such structural dispersion in the SERS spectra of 4-aminobenzothiol (4-ABT) and in its detection at low concentrations in solutions.

Triplet-State Position and Crystal-Field Tuning in Opto-Magnetic Lanthanide Complexes: Two Sides of the Same Coin.

Lanthanide-complex-based luminescence thermometry and single-molecule magnetism are two effervescent fields of research, owing to the great promise they hold from an application standpoint. The high thermal sensitivity achievable, their contactless nature, along with sub-micrometric spatial resolution make these luminescent thermometers appealing for accurate temperature probing in miniaturised electronics. To that end, single-molecule magnets (SMMs) are expected to revolutionise the field of spintronics, thanks to the improvements made in terms of their working temperature-now surpassing that of liquid nitrogen-and manipulation of their spin state.

A Luminescent Thermometer Exhibiting Slow Relaxation of the Magnetization: Toward Self-Monitored Building Blocks for Next-Generation Optomagnetic Devices.

The development and integration of Single-Molecule Magnets (SMMs) into molecular electronic devices continue to be an exciting challenge. In such potential devices, heat generation due to the electric current is a critical issue that has to be considered upon device fabrication. To read out accurately the temperature at the submicrometer spatial range, new multifunctional SMMs need to be developed.

Exploring the dual functionality of an ytterbium complex for luminescence thermometry and slow magnetic relaxation.

We present a comprehensive investigation of the magnetic and optical properties of an ytterbium complex, which combines two desirable and practical features into a single molecular system. Based upon Yb ions that promote near-infrared optical activity and a chemical backbone that is ideal for an in-depth understanding of the magnetic behaviour, we have designed a multifunctional opto-magnetic species that operates as a luminescent thermometer and as a single-molecule magnet (SMM). Our magnetic investigations, in conjunction with calculations, reveal one of the highest energy barriers reported for an Yb-based complex.

Estimating the Individual Spectroscopic Properties of Three Unique Eu Sites in a Coordination Polymer.

We isolated a coordination polymer with the formula [Eu(3,5-dcba)(HO)(dmf)]·2dmf, with three unique Eu coordination sites in the asymmetric unit, with the Eu ions bridged by 3,5-dichlorobenzoato (3,5-dcba) ligands. The coordination polymer crystallized in the triclinic space group P1̅ with unit cell dimensions a = 12.4899(15), b = 16.

Temperature probing and emission color tuning by morphology and size control of upconverting β-NaYbGdF:Tm:Ho nanoparticles.

The chemical composition, shape and size of upconverting nanoparticles are known to have a great influence on their spectroscopic properties, such as the emission color and the emission intensity variation as a function of temperature. This work shows the color tuning and the thermal sensitivity of NaYbGdF:Tm:Ho nanoparticles synthesized by two different approaches of the same synthetic method showing the influence of size and morphology, 250 nm hexagonal-plated and 30 nm spheroidal nanoparticles, on the visible upconversion color under NIR irradiation. According to the 1931-CIE diagram, the hexagonal-shaped nanoparticles show white light emission and the spheroidal ones generate red light emission under 980 nm excitation.

Estimating the Donor-Acceptor Distance To Tune the Emission Efficiency of Luminescent Lanthanide Compounds.

The influence of the donor-acceptor distance R on the photophysical properties, including the emission quantum yield, of two europium complexes with the same coordination number, and thus similar microsymmetries, was investigated by spectroscopic and computational methods. K[Eu(dipicCbz)] was synthesized using the new ligand dipicCbz and its photophysical properties compared to Cs[Eu(dipic)]. We found that a 50% increase in R from 4.