Anna Marta Kaczmarek

Two-dimensional (2D) hybrid organic–inorganic perovskites (HOIPs) offer structural versatility and tunable optoelectronic behavior arising from the interplay between their organic spacer layers and inorganic frameworks. In this work, we investigate how modifying the alkyl spacer length in benzotriazole (BTa)-based perovskites influences both the distortion of the lead-iodide layers and the resulting optical properties. Comparison between (BTaC2)2PbI4 and its three-carbon analogue (BTaC3)2PbI4 shows that the longer spacer unexpectedly decreases the penetration of the ammonium group into the inorganic layer, while accommodation of the longer alkyl chain increases in-plane Pb–I bond lengths and intraoctahedral distortion. Experimentally, (BTaC3)2PbI4 exhibits negligible octahedral tilting, unusually long average Pb–I bond lengths, and a pronounced alternation between long and short Pb–I bonds of 3.68 and 3.04 Å, respectively. First-principles calculations demonstrate that this atypical inorganic framework significantly influences its electronic structure. This dependence also manifests with a blue-shifted band gap and reduced photoluminescence intensity. Temperature-dependent X-ray diffraction and differential scanning calorimetry reveal that (BTaC3)2PbI4 undergoes a phase transition near 145 °C, in which the interdigitated organic bilayer reorganizes into a more conventional noninterdigitated arrangement, which preserves the 2D perovskite structure but removes intraoctahedral distortion, while reintroducing the interoctahedral tilting, as confirmed by three-dimensional electron diffraction (3DED). This phase transformation results in a substantial increase in photoluminescence intensity, accompanied by a blue shift in the emission band. The high-temperature phase is metastable at room temperature and converts back to the low-temperature interdigitated phase when exposed to elevated humidity. These findings clarify the connection between organic layer ordering, inorganic distortions, and the optical response in layered perovskites and indicate that humidity is an important trigger able to assist transitions between polymorphs.

We present a whole lanthanide (Ln) series of complexes, with a dipyrido phenazine ligand, derived from clinically used [Ln(DOTA)] complexes (DOTA = 1,4,7,10-tetraazadodecane-1,4,7,10-tetraacetic acid) for near-infrared luminescence applications.

This work highlights the potential of these hybrid particles as a versatile platform for integrated temperature sensing and drug delivery, with promising applications in theranostics.

This work presents a novel approach for detecting quench or hot spot regimes in coated conductors by depositing luminescent nanocrystals operating as nanothermometers onto the silver protective layer, allowing simultaneous temperature measurements.

A combination of experimental studies and kinetic modelling helps elucidate clear-cut guidelines for the use of the upconversion Tm ³⁺ , Yb ³⁺ system as a luminescent thermometer.

Accurate temperature measurements are important for cancer diagnosis, as localized temperature variations are often indicative of pathological conditions such as cancer and inflammation. The Nd³⁺-Yb³⁺ system is particularly promising due to its efficient energy transfer under 808 nm excitation, leading to distinct emissions from both ions in the second biological window (NIR-II, 1000–1700 nm). This spectral region is ideal for deep tissue imaging and temperature sensing, as it offers reduced scattering and absorption by biological tissues, enabling higher penetration depths and improved signal-to-noise ratios. This study presents a new hybrid thermometer composed of a silica core and a periodic mesoporous organosilica (PMO) shell decorated with LiLuF₄:Nd³⁺, Yb³⁺ nanoparticles, enabling temperature sensing and imaging in the NIR-II range. Additionally, these hybrid thermometers demonstrate drug release potential upon loading with doxorubicin as a model drug, indicating potential theranostic applications.

ConspectusOrganoboron-based crystalline compounds, which can respond to external stimuli (heat, light, electric field, or pressure), have already emerged as smart materials with well-directed functions. While various weak noncovalent interactions remain key to the supramolecular design, the exploitation of relatively strong boron-nitrogen dative bonds (B←N bonds) in constructing functional crystalline molecular and polymeric assemblies has recently attracted significant research interest. In particular, the strategic incorporation of B←N bonds into stimuli-responsive crystalline materials is promptly shaping a new direction in the field.Photomechanical or photodynamic crystals are a special kind of stimuli-sensitive smart material that can undergo rapid dynamic motions (jumping, bending, splitting, or curling) when exposed to UV/visible light. These instantaneous macroscopic crystal movements promoted by the used light source are collectively known as "photosalient effects". Metal-free/organic molecular crystals, exhibiting photosalient effects, provide an efficient choice of material to transform photon energy into mechanical work owing to their inherent lightweight, noncovalently bonded, and defectless packing. Therefore, such dynamic crystals are extremely relevant as an alternative to sustainable and flexible materials for soft robotics, actuators, energy storage, and sensors. These photodynamic crystal motions or photosalient effects can be induced by topochemical [2 + 2] cycloaddition reactions, mostly under high-energy UV light, as has recently been observed. In contrast, photodynamic motions triggered by visible light or even solar energy are less frequently encountered. However, topochemical [2 + 2] photoreactions do not always guarantee the exhibition of mechanical motions in crystals. While topochemical [2 + 2] photoreactivity has long been a subject of investigation, the study of photomechanical crystalline materials has only recently emerged as a key research focus.Following the pioneering work of Schmidt (Schmidt, G. M. J. Pure Appl. Chem. 1971, 27, 647-678 10.1351/pac197127040647), the topochemical [2 + 2] photodimerization reaction of olefins has arisen as a promising route to obtain novel crystalline materials with a wide variety of topologies and unique properties based on small organic molecules, discrete metal complexes, metal-coordination polymers, and organic polymers, which are otherwise not achievable by solution-phase synthesis. When any topochemical transformation proceeds to "completion" in a single-crystal-to-single-crystal (SCSC) manner, it carries invaluable structural and mechanistic information related to the crystal properties. In all these compounds, weak supramolecular interactions (hydrogen/halogen/chalcogen bonds or stacking interactions) and robust metal-coordinate bonds have been observed to direct [2 + 2] topochemical reactivity within the principle of crystal engineering. On the contrary, the organization of organoboron molecules in crystals, exhibiting photomechanical effects and solid-state reactions directed by B←N dative bonds, is seldom reported. Also, supramolecular B←N force-supported topochemical synthesis of crystalline organoboron polymers has yet to be explored.This Account summarizes our recent research progress on the design and development of molecular B←N bonded crystalline adducts that exhibit UV-to-visible light-induced macroscopic mechanical motions, accompanied by SCSC topochemical [2 + 2] dimerizations to polymerizations. We provide challenges and opportunities for future developments of B←N bond-directed photoresponsive crystalline materials within the context of crystal engineering, materials science, and organoboron chemistry. In brief, our work contributes to the rational design of efficiently energy-transducing photomechanical crystals based on molecular organoboron compounds, which undergo SCSC [2 + 2] photocycloaddition reactions to form novel molecular and polymeric crystalline materials.

Temperature measurements in biological systems deliver important information about the occurrence and location of diseases such as cancer. Also, certain therapies rely on local heating of tumor tissue, and therefore, feedback on the heating of nearby healthy tissue is valuable. However, classical thermometers are not suitable for precise temperature detection in living systems. Because of this, alternative ways to measure temperature, such as luminescence‐based thermometry, have been gaining interest and relevance for medical diagnostics and treatment support. In this work, LiLuF₄‐based nanocrystals are employed to develop novel ratiometric thermometers based on the rarely explored Ho³⁺‐Yb³⁺ and Nd³⁺‐Yb³⁺‐Ho³⁺ systems. After coating with a phospholipid bilayer, these thermometers show very good stability and thermometric performance in water and in skin‐mimicking tissue phantoms. The proposed Ho‐Yb‐Nd thermometry system allows constructing three separate thermometers within one material under one excitation wavelength. As there has been no scheelite single‐crystal structure of LiLuF₄ reported to date, its single‐crystal structure is determined with the use of three‐dimensional Electron Diffraction analysis (3D ED) employing highly crystalline nanoparticles (<50 nm), which emphasizes the exciting potential of 3D ED for determining the crystal structure of inorganic nanoparticles.

In this work, we report the synthesis of Na₃ZrF₇ nanoparticles as an appealing host matrix for lanthanide ions for both upconversion (bidoped, sensitizer-activator Yb³⁺-Er³⁺ in the vis and NIR-I regions) and downshifting (tridoped, sensitizer-activator-activator Yb³⁺-Ho³⁺-Er³⁺ in the NIR-II region) ratiometric luminescence nanothermometry in the physiological temperature range (293.15-323.15 K). We explored three different routes to reveal the most favorable synthetic approach for bioapplication purposes as well as investigated and characterized the temperature-dependent photoluminescence (PL) properties of the obtained nanoparticles. Furthermore, a biocompatible DSPE-PEG₂₀₀₀-based layer was incorporated to render the nanoparticles water-dispersible and to subsequently evaluate their degradation-induced in vitro toxicity toward HeLa and Normal Human Dermal Fibroblast (NHDF) cells. Additional in vitro tests were conducted to preliminarily evaluate the cellular uptake of the nanoparticles for future biological applications. We show that the synthetic conditions of the Na₃ZrF₇ nanoparticles and the solvent environment influence their morphology, crystalline phase, and PL emission profiles. To the best of our knowledge, this is the first effort at an extensive systematic synthesis approach for nanosized core-only and core-shell(s) Na₃ZrF₇ materials as ratiometric luminescent thermometers and the first reported temperature-sensing performance via Yb³⁺-Er³⁺ (NIR-I-to-vis) upconversion and Yb³⁺-Ho³⁺-Er³⁺ (NIR-I-to-NIR-II) downshifting mechanisms for this host material, both in cyclohexane and in an aqueous environment.

Lanthanide‐based luminescence nanothermometry has demonstrated unprecedented advantages in the development of nanotheranostic platforms for potential medical applications, yet despite exponential research progress and great enthusiasm across various related disciplines, a swift bench‐to‐bedside translation seems to be still out of reach. This is predominantly related to fundamental research issues at the preclinical stage, such as complex nanomaterials design, incomplete optimization, fragmented characterization, and insufficient validation of nanothermometer performance in physiological environments. The main impediments currently are important biophysicochemical issues that must be addressed comprehensively, first and foremost in available in vitro systems, before going on to in vivo investigations. This review outlines a critical perspective, as well as a route of suggestions and underexplored aspects to address and significantly minimize the existing translational gap.