Non-centrosymmetric Structure Research Articles

Crystallographic and Optical Spectroscopic Study of Metal–Organic 2D Polymeric Crystals of Silver(I)– and Zinc(II)–Squarates

Metal–organic framework materials, as innovative functional materials for nonlinear optical technologies, feature linear and nonlinear optical responses, such as a laser damage threshold, outstanding mechanical properties, thermal stability, and optical transparency. Their non-centrosymmetric crystal structure induces a higher-order nonlinear optical response, which guarantees technological applications. ZnII– and AgI–squarate complexes are attractive templates for these purposes due to their good crystal growth, optical transparency, high thermal stability, etc. However, the space group type of the catena-((μ2-squarato)-tetra-aqua-zinc(II)) complex ([Zn(C4O4)(H2O)4]) is debatable, (1) showing centro- and non-centrosymmetric monoclinic C2/c and Cc phases. The same is valid for the catena-((μ3-squarato)-(μ2-aqua)-silver(I)) complex (Ag2C4O4), (2) exhibiting, so far, only a C2/c phase. This study is the first to report new crystallographic data on (1) and (2) re-determined at different temperatures (293(2) and 300(2)K) and the non-centrosymmetric Cc phase of (2), having different numbers of molecules per unit cell compared with the C2/c phase. There are high-resolution crystallographic measurements of single crystals, experimental electronic absorption, and vibrational spectroscopic data, together with ultra-high-resolution mass spectrometric ones. The experimental results are supported for theoretical optical and nonlinear optical properties obtained via high-accuracy static computational methods and molecular dynamics, using density functional theory as well as chemometrics.

Deconvolution of X-ray natural and magnetic circular dichroism in chiral Dy-ferroborate.

Structural chirality and magnetism, when intertwined, can have profound implications on materials properties. Using X-ray imaging and spectroscopic measurements that leverage the natural and magnetic circular dichroic effects present in magnetized chiral crystal structures, we probe the interplay between chirality and magnetism across the field-induced spin-flop transition of Dy ferroborate, ( ) . Deconvolution of natural and magnetic circular dichroic signals at the Fe K and Dy L absorption edges of the non-centrosymmetric structure was enabled by use of tunable temperature and magnetic field, providing access to element-specific magnetic information across the spin-flop transition. The magnetic response of Fe and Dy sublattices was found to be independent of domain chirality. The chiral domains were robust against both the (chirality preserving) R32 to P3 21/P3 21 structural phase transition at 280 K, and application of magnetic field up to 4 Tesla. A third flavor of X-ray dichroism, magneto-chiral dichroism, was not detected within the accuracy of our measurements. The absence of significant Fe magnetization along the screw, c-axis for the magnetic field strength used in this study, together with non-linear coupling of magnetic field to electric polarization across the spin-flop transition, may hinder observation of magneto-chiral dichroic effects in this system.

Engineering of the High‐Power Laser‐Induced Synthesis of Ni‐Based Metal‐Organic Framework: Investigation of its Optical Properties, Computational Methodology, Electrocatalytic Performances, and Glucose‐Sensing Ability

AbstractMetal‐organic frameworks (MOFs) are porous materials with numerous chemical and structural possibilities. Due to their ease of modification, well‐organized structure, and diverse guest molecule chemistry, MOFs are ideal platforms for uncovering improved functional material design characteristics. Quantitative analysis of glucose is crucial, especially in some food products, for quality control as well as evaluation of the glucose levels helps diagnose and treat diabetes. Recent glucose sensing devices have relied heavily on MOFs and other nanomaterials to enable user‐friendly and safe non‐invasive sensing methods. Nevertheless, the conventional synthesis methods involve multi‐day reactions, cooling, and depressurization processes. This study demonstrates the unprecedented high‐power laser‐induced rapid synthesis (LIRS) of Ni‐based MOF nanospheres with interconnected nano‐rods and noncentrosymmetric primitive triclinic crystalline structure, highlighting their multifunctional usage in sensing and gas sorption applications. Ab initio simulations show excellent agreement with the experimental physical and gas sorption properties. Furthermore, the Ni‐MOF‐based biosensor accurately measures glucose real‐life beverage samples, yielding promising glucose detection biosensor results with a low limit of the detection (LOD) of 13.96 µM and high sensitivity of 120.606 µA mM−1 cm−2.

Synthesis and Characterization of Low-Dimensional Quaternary Sulfides of Thallium, Tl2Cu2GeS4, Tl2Ag2GeS4, and Tl2Ag2SnS4.

Three new low-dimensional quaternary sulfides, namely, Tl2Cu2GeS4(1), Tl2Ag2GeS4(2), and Tl2Ag2SnS4(3) were synthesized by solid-state reactions and characterized by single-crystal X-ray diffraction, spectroscopic, thermal, and photocatalytic studies. The compounds 1, 2, and 3, respectively, have centrosymmetric layered, noncentrosymmetric layered, and noncentrosymmetric one-dimensional structures, in which Cu+, Ge4+, and Sn4+ ions have tetrahedral coordination and Ag+ ion has linear, trigonal planar and tetrahedral coordinations. The monovalent thallium cations have TlS8 dodecahedral coordination and TlS7 and TlS6 coordination polyhedra of irregular shape. The compounds 1, 2, and 3 are semiconductors with the respective energy band gap values of 1.68, 2.02, and 1.90 eV. Compared to compounds 1 and 2, compound 3 has a higher efficiency value of 22.9% for the photodegradation of aqueous solution of methylene blue. Band structures and projected density of states of all three compounds were computed using density functional theory, and these results are in good agreement with experiments.

Unveiling the recently synthesis noncentrosymmetric layered ASb3X2O12 (A = K, Rb, Cs, Tl; X = Se, Te) via first principles calculations

This study explores the structural, optical, and thermoelectric properties of non-centrosymmetric layered selenite and tellurite compounds KSb3Se2O12, RbSb3Se2O12, CsSb3Se2O12, TlSb3Se2O12, KSb3Te2O12, RbSb3Te2O12, CsSb3Te2O12, TlSb3Te2O12 to assess their potential for sustainable and renewable energy technologies. The selenite and tellurite compounds feature distinct non-centrosymmetric layered crystal structures, which are key to their unique optical and electronic properties. The materials display a layered structure without a center of symmetry, characterized by distinct atomic arrangements, and their band gaps vary depending on the constituent elements. For selenites, band gaps range from 2.97 eV to 3.19 eV, while for tellurites, they range from 2.75 eV to 3.02 eV, indicate their suitability for indirect semiconducting applications. The investigated materials exhibit high absorbance in the ultraviolet region, suggesting they are promising for solar cell applications. The energy loss function peaks at 14 eV, indicating minimal optical loss in the infrared and visible spectra. The static dielectric constants ε1(0) were calculated, showing variations based on the elemental composition. The response of ε2(ω) demonstrates strong interactions in the ultraviolet region, corresponding to electronic transitions from the valence to the conduction bands. Thermoelectric properties, evaluated with the BoltzTrap code using transport theory. The Seebeck coefficient of p-type semiconductors typically increases with temperature, but TlSb3Se2O12 shows an even greater increase, suggesting enhanced thermoelectric properties. Both selenites and tellurites have rising electrical conductivities, with ASb3Se2O12 peaking at 800 K. The Power Factor improves with temperature, reaching a peak for TlSb3Se2O12. These compounds exhibit favorable electrical conductivity and power factor, suggesting potential applications in thermoelectric systems. The figure of merit (ZT) values spanning from 0.90 to 1.51, with a maximum ZT value of 1.41 at 800 K, TlSb3Se2O12 shows great potential for high-temperature thermoelectric applications. These findings advance the understanding of non-centrosymmetric oxide materials and provide valuable insights for developing advanced materials for energy technologies.

Unconventional pairing in Ising superconductors: application to monolayer NbSe2

Abstract The presence of a non-centrosymmetric crystal structure and in-plane mirror symmetry allows an Ising spin–orbit coupling to form in some two-dimensional materials. Examples include transition metal dichalcogenide superconductors like monolayer NbSe2, MoS2, TaS2, and PbTe2, where a nontrivial nature of the superconducting state is currently being explored. In this study, we develop a microscopic formalism for Ising superconductors that captures the superconducting instability arising from a momentum-dependent spin- and charge-fluctuation-mediated pairing interaction. We apply our pairing model to the electronic structure of monolayer NbSe2, where first-principles calculations reveal the presence of strong paramagnetic fluctuations. Our calculations provide a quantitative measure of the mixing between the even- and odd-parity superconducting states and its variation with Coulomb interaction. Further, numerical analysis in the presence of an external Zeeman field reveals the role of Ising spin–orbit coupling and mixing of odd-parity superconducting state in influencing the low-temperature enhancement of the critical magnetic field.

Structural design and characterization of a new type of organic nonlinear optical flavanone crystal

Two new crystals were designed and obtained: the chalcone derivative HMMP (1-(2‑hydroxy-4-methoxyphenyl)-3-(4-(methylthio)phenyl)prop‑2-en-1-one) and the flavanone derivative 7M4MC (7‑methoxy-2-(4-(methylthio)phenyl)chroman-4-one). Yellow bulk 7M4MC single crystal with dimensions of 3 × 2 × 1 mm3 and orange-yellow needle-like HMMP single crystal were grown by solution evaporation. 7M4MC crystal belongs to the P21 space group of the monoclinic structure, which has a non-centrosymmetric structure. HMMP crystal monoclinic, belongs to the P21/m space group with a centrosymmetric structure. In the 7M4MC molecule, the methoxy and methylthio groups act as electron donors (D) and the carbonyl group acts as an electron acceptor (A), forming a d-π-A-π-D structure with an electron gradient. 7M4MC exhibits a high degree of second-harmonic generation intensity (11 × KDP), a broad transmission range (600–1600 nm, >88 %), an elevated optical energy bandgap (Eg = 2.57 eV), high thermal stability (Tm = 105 °C) and excellent dielectric properties (εr ≈ 2.1). This work not only provides two new crystals but also offers a viable molecular design option by changing the degree of intramolecular distortion by altering the backbone structure.

Piezoelectric-induced mechanoluminescence in centrosymmetric Lu3Al5O12: Properties of self-recoverable and tunable near-infrared luminescence

Mechanoluminescence (ML) materials with long-wavelength emission bands are essential for future in vivo bioimaging, non-destructive testing. However, most of the near-infrared (NIR) ML materials require pre-irradiation, which may limit their further applications. Generally, piezoelectric-induced ML materials were considered to be related to the piezoelectric effect from non-centrosymmetric structure. Innovatively in this work, a novel piezoelectric-induced near-infrared ML material Lu3Al5O12:Cr3+ with centrosymmetric structure is obtained. In Lu3Al5O12:Cr3+, piezoelectric effect is generated from the distortion of the centrosymmetric structure of the host due to the uneven electron distribution of Cr3+. Here, highly tunable ML FWHM from 7 nm to 118 nm is realized by introducing different content Ga3+ ions to Lu3Al5O12:Cr3+. The ML film fabricated by composite polydimethylsiloxane and Lu3Al2Ga3O12:Cr3+ can penetrate 20 mm pork tissue, which suggests the potential applications of the NIR ML material in the field of optical imaging of stress distribution in organisms. The discovery of distorted crystal structure to induce piezoelectric effect provides a new thinking for exploring ML in centrosymmetric materials. In addition, LuAl5-xGaxO:Cr3+ phosphors have broad prospects in self-powered sensing, temporomandibular disorders diagnosis, information security, and biomedical fields.

Effect of thermal annealing on the average and local structure of superconducting polycrystalline NbRe films

Abstract NbxRe1−x is a non-centrosymmetric superconductor recently realized in thin film form. The access to the basic physics that governs this material is hindered by the polycrystalline structure of the films which consist of grains of small dimensions. In these conditions, films are not decisive in revealing the nature of the superconducting order parameter, and, in particular, the possible presence of a spin-triplet component. In this work, post-deposition annealing procedures were performed to improve the crystalline quality of the as-grown films. As determined by X-ray diffraction measurements, by tuning the annealing process, it was possible to increase the crystalline size from 1-2 nm up to several nanometers, beyond the values of the superconducting coherence length. Pair distribution function analyses revealed the non-centrosymmetric crystal structure of the treated NbRe films. Finally, electrical transport measurements, performed to study the relationship between structural and transport properties of the samples, showed an improved metallicity and a reduction of the superconducting critical temperature after the thermal treatment. This last result can be reasonably ascribed, for instance, to oxygen contamination, modification of the electronic density of states at the Fermi level, or change in the electron-phonon coupling. The results of this work are useful to realize films for future experiments meant to access nature of the superconducting order parameter.

Ferromagnetic quantum critical point protected by nonsymmorphic symmetry in a Kondo metal

Quantum critical points (QCPs), zero-temperature phase transitions, are windows to fundamental quantum-mechanical phenomena associated with universal behaviour. Magnetic QCPs have been extensively investigated in the vicinity of antiferromagnetic order. However, QCPs are rare in metallic ferromagnets due to the coupling of the order parameter to electronic soft modes. Recently, antisymmetric spin-orbit coupling in noncentrosymmetric systems was suggested to protect ferromagnetic QCPs. Nonetheless, multiple centrosymmetric materials host FM QCPs, suggesting a more general mechanism behind their protection. In this context, CeSi2-δ, a dense Kondo lattice crystallising in a centrosymmetric structure, exhibits ferromagnetic order when Si is replaced with Ag. We report that the Ag-substitution to CeSi1.97 linearly suppresses the ferromagnetic order towards a QCP, accompanied by concurrent strange-metal behaviour. Herein, we suggest that, despite the centrosymmetric structure, spin-orbit coupling arising from the local noncentrosymmetric structure, in combination with nonsymmorphic symmetry, can protect ferromagnetic QCPs. Our findings offer a general guideline for discovering new ferromagnetic QCPs and highlight one new family of materials within which the interplay of topology and quantum phase transitions can be investigated in the context of strongly correlated systems.

Polar Thiazole Derivative-Induced Second Harmonic Response in Hybrid Bismuth Chlorate with Reversible Photochromism.

Inorganic-organic hybrid bismuth halides demonstrate great prospect in the field of second-order nonlinear optical (NLO) crystals because the ns2 electron on Bi(III) could lead to large molecular polarization and high second harmonic generation (SHG) coefficient on a noncentrosymmetric structure. However, researchers cannot yet control the effective arrangements of the bismuth halide functional motif, which results in SHG-active hybrid bismuth halides being rare. Herein, thiazole derivatives with a polar donor-π-acceptor system are designed to explore hybrid bismuth halide NLO crystals. The protonated 2-(4-hydroxyphenyl) thiazole (denoted as hpt) interacts with the (BiCl6) motif via H···Cl hydrogen bonds to prevent antiparallel arrangements, which therefore enhance the NLO property. (Hhpt)3[BiCl6] crystallizes in the monoclinic polar P21 space group, which exhibits a strong SHG response and reversible photochromic behavior. Structural analysis and theory calculations reveal that the synergistic effect between the polar thiazole derivative and the distorted inorganic [BiCl6]3- motif is responsible for the SHG response. This is the first report of polar thiazole derivative-induced SHG-active hybrid bismuth halide coupled with reversible photochromism.

Synergistic Interactions of Bulk Polarization and Built-In Electric Field Inducing 2D/2D S-Scheme Homojunction Toward Enhanced Photocatalytic Performance.

The rational design of S-scheme photocatalysts, achieved by serially integrating two different semiconductors, represents a promising strategy for efficient charge separation and amplified photocatalytic performance, yet it remains a challenge. Herein, ZnIn2S4 (ZIS) and oxygen-doped ZnIn2S4 (O-ZIS) nanosheets are chosen to construct a homojunction catalyst architecture. Theoretical simulations alongside comprehensive in situ and ex situ characterizations confirm that ZIS and O-ZIS with noncentrosymmetric layered structures can generate a polarization-induced bulk-internal electric field (IEF) within the crystal. A robust interface-IEF is also created by the strong interfacial interaction between O-ZIS and ZIS with different work functions. Owing to these features, the O-ZIS/ZIS homojunction adopts an S-scheme directional charge transfer route, wherein photoexcited electrons in ZIS and holes in O-ZIS concurrently migrate to their interface and subsequently recombine. This enables spatial charge separation and provides a high driving force for both reduction and oxidation reactions simultaneously. Consequently, such photocatalyst exhibits an H2 evolution rate up to 142.9µmol h-1 without any cocatalysts, which is 4.6- and 3.4-fold higher than that of pristine ZIS and O-ZIS, respectively. Benzaldehyde is also produced as a value-added oxidation product with a rate of 146.9µmol h-1. This work offers a new perspective on the design of S-scheme systems.

Exposing the odd-parity superconductivity in CeRh2As2 with hydrostatic pressure

Odd-parity superconductivity is a fundamentally interesting but rare state of matter with a potential for applications in topological quantum computing. Crystals with staggered locally noncentrosymmetric structures have been proposed as platforms where a magnetic field can induce a transition between even- and odd-parity superconducting (SC) states. The strongly correlated superconductor CeRh2As2, with the critical temperature Tc≈0.4K, is likely the first example material showing such a phase transition, which occurs at the magnetic field μ0H*=4T applied along the crystallographic c axis. CeRh2As2 also undergoes a phase transition of an unknown origin at T0=0.5K. By subjecting CeRh2As2 to hydrostatic pressure and mapping the resultant changes to the SC phase diagrams we investigated how the lattice compression and changes to the electronic correlations affect the stability and relative balance of the two SC states. The abnormally high in-plane upper critical field becomes even higher close to a quantum critical point of the T0 order. Remarkably, the SC phase-switching field H* is drastically reduced under pressure, dropping to 0.3 T at 2.7 GPa. This result signals an apparent strengthening of the local noncentrosymmetricity and forecasts a possible stabilization of the putative odd-parity state down to zero field, hitherto not considered by theoretical models. Published by the American Physical Society 2024

Pressure-Tuned Quantum Criticality in the Locally Noncentrosymmetric Superconductor CeRh_{2}As_{2}.

The unconventional superconductor CeRh_{2}As_{2} (critical temperature T_{c}≈0.4 K) displays an exceptionally rare magnetic-field-induced transition between two distinct superconducting (SC) phases, proposed to be states of even and odd parity of the SC order parameter, which are enabled by a locally noncentrosymmetric structure. The superconductivity is preceded by a phase transition of unknown origin at T_{0}=0.5 K. Electronic low-temperature properties of CeRh_{2}As_{2} show pronounced non-Fermi-liquid behavior, indicative of a proximity to a quantum critical point (QCP). The role of quantum fluctuations and normal state orders for the superconductivity in a system with staggered Rashba interaction is currently an open question, pertinent to explaining the occurrence of the two-phase superconductivity. In this work, using measurements of resistivity and specific heat under hydrostatic pressure, we show that the T_{0} order vanishes completely at a modest pressure of P_{0}≈0.5 GPa, revealing a QCP. In line with the quantum criticality picture, the linear temperature dependence of the resistivity at P_{0} evolves into a Fermi-liquid quadratic dependence as quantum critical fluctuations are suppressed by increasing pressure. Furthermore, the domelike behavior of T_{c} around P_{0} implies that the fluctuations of the T_{0} order are involved in the SC pairing mechanism.

Multimodal Molecular Imaging Reveals a Novel Membrane Component in Sporangia of the Rare Actinomycete Actinoplanes missouriensis.

The bacterium Actinoplanes missouriensis belongs to the genus Actinoplanes, a prolific source of useful natural products. This microbe forms globular structures called sporangia, which contain many dormant spores. Recent studies using transmission electron microscopy have shown that the A. missouriensis sporangium membrane has an unprecedented three-layer structure, but its molecular components remain unclear. Here, we present multimodal (spontaneous Raman scattering, coherent anti-Stokes Raman scattering, second harmonic generation, sum frequency generation, and third-order sum frequency generation) label-free molecular imaging of intact A. missouriensis sporangia. Spontaneous Raman imaging assisted with multivariate curve resolution-alternating least-squares analysis revealed a novel component in the sporangium membrane that exhibits unique Raman bands at 1550 and 1615 cm-1 in addition to those characteristic of lipids. A plausible candidate for this component is an unsaturated carbonyl compound with an aliphatic moiety derived from fatty acid. Furthermore, second harmonic generation imaging revealed that a layer(s) of the sporangium membrane containing this unknown component has an ordered, noncentrosymmetric structure like fibrillar proteins and amylopectin. Our results suggest that the sporangium membrane is a new type of biological membrane, not only in terms of architecture but also in terms of components. We demonstrate that multimodal molecular imaging with Raman scattering as the core technology will provide a promising platform for interrogating the chemical components, whether known or unknown, of diverse biological structures produced by microbes.

Two-Dimensional Atomically Thin Piezoelectric Nanosheets for Efficient Pyroptosis-Dominated Sonopiezoelectric Cancer Therapy.

Sonopiezocatalytic therapy is an emerging therapeutic strategy that utilizes ultrasound irradiation to activate piezoelectric materials, inducing polarization and energy band bending to facilitate the generation of reactive oxygen species (ROS). However, the efficient generation of ROS is hindered by the long distance of charge migration from the bulk to the material surface. Herein, atomically thin Bi2O2(OH)(NO3) (AT-BON) nanosheets are rationally engineered through disrupting the weaker hydrogen bonds within the [OH] and [NO3] layer in the bulk material. The ultrathin structure of AT-BON piezocatalytic nanosheets shortens the migration distance of carriers, expands the specific surface area, and accelerates the charge transfer efficiency, showcasing a natural advantage in ROS generation. Importantly, the non-centrosymmetric polar crystal structure grants the nanosheets the ability to separate electron-hole pairs. Under ultrasonic mechanical stress, Bi2O2(OH)(NO3) nanosheets with the remarkable piezoelectric feature exhibit the desirable in vivo antineoplastic outcomes in both breast cancer model and liver cancer model. Especially, the AT-BON-induced ROS bursts lead to the activation of the Caspase-1-driven pyroptosis pathway. This study highlights the beneficial impact of bulk material thinning on enhancing ROS generation efficiency and anti-cancer effects.

Fermi Surface Nesting with Heavy Quasiparticles in the Locally Noncentrosymmetric Superconductor CeRh2As2

Abstract The locally noncentrosymmetric heavy fermion superconductor CeRh2As2 has attracted considerable interests due to its rich superconducting phases, accompanied by possible quadrupole density wave and pronounced antiferromagnetic excitations. To understand the underlying physics, here we report measurements from high-resolution angle-resolved photoemission. Our results reveal fine splittings of the conduction bands related to the locally noncentrosymmetric structure, as well as a quasi-two-dimensional Fermi surface (FS) with strong 4f contributions. The FS shows signs of nesting with an in-plane vector q 1 = (π/a, π/a), which is facilitated by the heavy bands near X ¯ arising from the characteristic conduction-f hybridization. The FS nesting provides a natural explanation for the observed antiferromagnetic spin fluctuations at (π/a, π/a), which might be the driving force for its unconventional superconductivity. Our experimental results can be reasonably explained by density functional theory plus dynamical mean field theory calculations, which can capture the strong correlation effects. Our study not only provides spectroscopic signature of the key factors underlying the field-induced superconducting transition, but also uncovers the critical role of FS nesting and lattice Kondo effect in the underlying magnetic fluctuations.

Hydrogen bond-derived symmetry transformation in hydroxyborates: Converting the nonlinearity from null to active

Non-centrosymmetric structure is the prerequisite to symmetry-dependent properties for functional materials. The inherent tendency of crystallization toward centrosymmetric arrangements has posed a great challenge in nonlinear optical crystals that requires non-centrosymmetric structure. Here we discovered two new hydroxyborates A[C(NH2)3][B4O5(OH)4]·nH2O (A = K, Rb; n = 3, 1.5), which have high similarity in cationic and anionic frameworks but clearly differ in terms of symmetry, such as non-centrosymmetric versus centrosymmetric. Variations in the hydrogen bonds of water molecules in the lattice are confirmed to be the origin of the symmetry breaking and transformation. The effectiveness of hydrogen bond-derived molecular engineering in producing non-centrosymmetric structure and opening up new avenues in the nonlinear optical crystal sector is demonstrated in this work.

Investigations of structure, thermal stability and optical properties of a new NLO crystal (C3H5N2)+(CF3COO)-

New NLO imidazolium trifluoro acetate (C3H5N2)+(CF3COO)- single crystals were synthesized by solution evaporation method, with its structure, thermal stability, absorption spectrum, photoluminescence and second order nonlinear optical (NLO) properties were systematically investigated. This crystal features 0-dimensional noncentrosymmetric structure with orthorhombic space group I212121 which consist of isolated organic imidazolium cation (C3H5N2)+ and trifluoro acetate anion (CF3CO2)-. A high thermal stability up to 125 °C, and the absorption edge at 260 nm with a wide band gap of 4.55 eV were respectively determined. In addition, the photoluminescence performance with an emission peak at 363 nm can be ascribed to the π-π* transition absorption of imidazole ring. Notably, moderate phase-matching SHG response of 0.64 times KH2PO4 was evaluated for (C3H5N2)+(CF3COO)-. All the results indicate the potential applications of (C3H5N2)+(CF3COO)- in optical field.

Recycling of human teeth for piezoelectric energy harvesting

In the human body, non-centrosymmetric biological structures exhibit piezoelectric effect across from microscopic biomolecular building blocks to macroscopic tissues and organs. However, the fabrication of piezoelectric devices from discarded natural tissues and organs has rarely been exploited for energy harvesting applications. Herein, the extracted human teeth were recycled as an active layer in a piezoelectric nanogenerator for power generation. Due to the piezoelectric effect of enamel and dentin, a human teeth-based sandwiched piezoelectric nanogenerator was fabricated, producing high and stable power outputs with an open-circuit voltage of approximately 0.9 V under an external force at 60 N. Furthermore, the high mechanical durability of the piezoelectric nanogenerator was also verified after 1600 pressing-and-releasing cycles without noticeable output degradation. Notably, for the first time, a light-emitting diode (LED) was illuminated by the human teeth-based piezoelectric device. This work exemplifies a sustainable strategy to recycle the extracted human teeth by fabricating a piezoelectric nanogenerator for energy harvesting, providing inspiration for converting waste into wealth toward green energy in bionanotechnology.