Novel Spatially Asymmetric Copper Bismuthate-Mediated Augmentation of Energy Conversion to Realize "Three-Step" Tumor Suppression.

The generally undesirable bandgap and electron-hole complexation of inorganic sonosensitizers limit the efficiency of reactive oxygen species (ROS) generation, affecting the effectiveness of sonodynamic therapy (SDT). Comparatively, the novel polyvinylpyrrolidone-modified copper bismuthate (PCBO) sonosensitizers are manufactured for a "three-step" SDT promotion. In brief, first, the strong hybridization between Bi 6s and O 2p orbitals in PCBO narrows the bandgap (1.83 eV), facilitating the rapid transfer of charge carriers. Additionally, nonequivalent [CuO4]6- layers reduce crystal symmetry, confer PCBO unique piezoelectricity, and improve electron-hole separation under ultrasonic (US) excitation. This allows PCBO to convert US energy into chemical energy to produce ROS, achieving the accumulation of abundant ROS, resulting in apoptosis and tumor suppression. Concurrently, PCBO also acts as a glutathione scavenger to reduce tumor antioxidant capacity and improve efficacy. To the best of authors understanding, this study reveals PCBO as an innovative piezoelectric sonosensitizer and provides a meaningful paradigm for designing energy conversion strategies for tumor suppression.

Bright white light emission from lanthanide oxide LaGdO3 for LED lighting by Bi3+ to Eu3+ energy transfer.

Phosphors with intrinsic white light emission are of great potential in constructing high-quality white LEDs (WLEDs). In this work, we propose the use of energy transfer from Bi3+ to Eu3+ ions for white light emission. A unique Bi3+-activated phosphor LaGdO3 (LGO):Bi3+ was generated using the conventional high-temperature solid-state process. An energy transfer was established by introducing Eu3+ into the phosphor composition. The emission colour of LGO:Bi3+,Eu3+ phosphors changes from cyan to white to orange-red depending on the Bi3+/Eu3+ doping proportion. The energy transfer between the Bi3+ and Eu3+ ions results from the dipole-dipole interaction. The LGO:Bi3+,Eu3+ phosphors were combined with a near-ultraviolet chip to successfully create a single-component WLED device with a colour-rendering index of 92.4. Our work demonstrates the energy transfer as a route for single-component white light emission and makes LGO:Bi3+,Eu3+ phosphors one of the candidate materials for near-ultraviolet lighting.

Hydrothermal synthesis of ZnGa2O4 nanophosphors with high internal quantum efficiency for near-infrared pc-LEDs.

NIR luminescent materials have garnered widespread attention because of their exceptional properties, with high tissue penetration, low absorption and high signal-to-noise ratio in the field of optical imaging. However, producing nanophosphors with high quantum yields of emitting infrared light with wavelengths above 1000 nm remains a significant challenge. Here, we prepared a nanoscale ZnGa2O4:xCr3+,yNi2+ phosphor with good luminescence performance in near-infrared emission, which was synthesized via a hydrothermal method and subsequent calcination process. By co-doping with Cr3+ and Ni2+, the ZnGa2O4 phosphor shows a strong broadband emission of 1100-1600 nm in the second near-infrared (NIR-II) region, owing to the energy transfer from Cr3+ to Ni2+ with an efficiency up to 90%. Meanwhile, a near-infrared phosphor-conversion LED (NIR pc-LED) device is fabricated based on the ZnGa2O4:0.8%Cr3+,0.4%Ni2+ nanophosphor, which has under 100 mA input current, an output power of 23.99 mW, and a photoelectric conversion efficiency of 7.53%, and can be effectively applied in imaging and non-destructive testing. Additionally, the intensity ratio of INi/ICr of ZnGa2O4:0.8% Cr3+,0.4%Ni2+ with its high sensitivity value of 4.21% K-1 at 453 K under 410 nm excitation, indicates its potential for thermometry application.

Well-Performed Green Phosphor BaY4Si5O17:Ce3+,Tb3+ with High Quantum Efficiency and Thermal Stability.

For Tb3+-doped green phosphors, the energy transfer from Ce3+ to Tb3+ can largely enhance the absorption of excitation; however, obtaining phosphors that exhibit both high quantum efficiency and thermal stability continues to pose a significant challenge. Herein, we established a paradigm to achieve novel silicate BaY4Si5O17 (BYSO):Ce3+,Tb3+. The near-ultraviolet light efficiently excites the BYSO:Ce3+ material, causing it to emit light at a wavelength of 408 nm. The photoluminescence of BYSO:0.12Ce3+ exhibits a relatively small Stokes shift and a thermal stability of 89.8% of the 303 K emission intensity at 423 K (89.8%@423 K). The energy transfer (ET) from Ce3+ to Tb3+ ions can be readily constructed in BYSO:Ce3+,Tb3+ utilizing the overlap between the Ce3+ emission and the Tb3+ excitation. The ET efficiency from the Ce3+ to Tb3+ ions reached 83.8% at y = 1.2 and a maximum of 94.6%. Finally, the optimized phosphor BYSO:0.12Ce3+,1.2Tb3+ had an internal quantum efficiency of 94.4% and had excellent thermal stability (96.1%@423 K). Our work pointed out the avenue to novel green phosphors with high efficiency and thermal stability by choosing appropriate host and construct efficient ET.

An efficient blue-violet phosphor: an advanced material designed for high-quality full-spectrum lighting.

A highly efficient phosphor with exceptional luminescence properties is crucial for achieving high-quality solid-state white-light illumination. Here, this paper presents a groundbreaking discovery, an innovative blue-violet emitting Ba1.31Sr3.69(BO3)3Cl:Ce3+ (BSBCl:Ce3+) phosphor designed with remarkable thermal stability and quantum efficiency for full spectrum white light-emitting diodes (WLEDs). By employing a high-temperature solid-phase method, we synthesized various BSBCl:xCe3+ phosphors with different Ce3+ doping concentrations. Remarkably, BSBCl:0.03Ce3+ displays a broad excitation band from 250 nm to 400 nm, rendering it compatible with commercial near-ultraviolet (UV) LED chips. Under 330 nm excitation, this phosphor emits blue light with an astonishing 88.2% internal quantum efficiency (IQE) and an impressive 60.9% external quantum efficiency (EQE). Notably, when employed in the temperature range of 298-473 K, the synthesized BSBCl:0.03Ce3+ phosphor exhibits exceptional color stability and thermal stability (I423 K/I298 K = 83%). Utilizing BSBCl:0.03Ce3+ as the blue-violet emitting component in the fabrication of WLED devices has demonstrated significant advancements in the color rendering index. These findings underscore the potential of BSBCl:Ce3+ phosphors for a wide range of applications in health-oriented indoor illumination.

Remote Control and Noninvasive Detection Enabled by a High-performance NIR pc-LED.

In an increasing manner, near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs) are considered to be exemplary light sources owing to their notable attributes of elevated output power, economical nature, and exceptional portability. NIR phosphors are critical components of NIR pc-LEDs. Herein, we report a novel blue light excitable NIR phosphor CaLu2ZrScAl3O12:Cr3+ (CLZSA:Cr3+) as a crucial and efficient broadband NIR emitter. The CLZSA:Cr3+ phosphor displays an intense NIR broadband emission peaking at 776 nm and with a full width at half-maximum (fwhm) of 140 nm. The designed material also exhibits superior resistance to thermal quenching, as the intensity of emission at 423 K remains at 80% of that at room temperature. The constructed NIR pc-LED device based on CLZSA:Cr3+ demonstrates a high total output power of 68.4 mW at a drive current of 100 mA, along with a high photoelectric conversion efficiency of 23.0%. Impressively, the high-power NIR pc-LEDs are utilized as light sources for remote control and non-invasive detection, resulting in the excellent performance and remarkable achievement.

High Output Power and High Quantum Efficiency in Novel NIR Phosphor MgAlGa0.7 B0.3 O4 :Cr3+ with Profound FWHM Variation.

There is strong demand for ultraefficient near-infrared (NIR) phosphors with adjustable emission properties for next-generation intelligent NIR light sources. Designing phosphors with large full-width at half-maximum (FWHM) variations is challenging. In this study, novel near-ultraviolet light-emitting diode (LED)-excited NIR phosphors, MgAlGa0.7 B0.3 O4 :Cr3+ (MAGBO:Cr3+ ), with three emission centers achieve ultra-narrowband (FWHM = 29 nm) to ultra-broadband (FWHM = 260 nm) emission with increasing Cr3+ concentration. Gaussian fitting and decay time analysis reveal the alteration in the FWHM, which is attributed to the energy transfer occurring between the three emission centers. The distinct thermal quenching behaviors of the three emission centers are revealed through the temperature-dependent decay times. The ultra-broadband NIR phosphor MAGBO:0.05Cr3+ exhibits high thermal stability (85%, 425 K) and exceptional external quantum efficiency of 68.5%. An NIR phosphor-converted LED (pc-LED) is fabricated using MAGBO:0.05Cr3+ phosphor, exhibiting a remarkable NIR output power of 136 mW at 600 mA in ultra-broadband NIR pc-LEDs. This study describes the preparation of highly efficient phosphors and provides a further understanding of the tunable FWHM, which is vital for high-performance NIR phosphors with versatile applications.

Crystal Field Engineering Yields New 3D Layered Solid Solution Phosphors (Ca/Sr)4MgAl2Si3O14:Eu2+ for White-Light-Emitting Diode Full-Spectrum Lighting.

The cation-equivalent substitution strategy has the ability to manipulate the luminescence color of phosphors and enhance their overall luminescence performance. A series of novel yellow feldspar-type 3D layered phosphors (Ca1-ySry)4MgAl2Si3O14:xEu2+ were synthesized using a high-temperature solid-state reaction. The solid solution phosphors belong to a tetragonal crystal system with a space group of P4̅21m and cell parameters of a = b = 7.75407-7.91794 Å, c = 5.04299-5.22543 Å, and V = 303.166-327.602 Å3. Under near-ultraviolet (n-UV) excitation, the luminescence color of the phosphor undergoes modulation from yellow-green (530 nm) to blue (467 nm) as the Sr2+ ion substitution ratio increases. This modulation is attributed to the gradual decrease in crystal field splitting energy. Additionally, both the Stokes shift and the full width of the luminescence spectra decrease. Furthermore, there is an increase in the quantum yield (QY) from 45.50 to 60.73%. Finally, the fabricated white-light-emitting diode devices emitted warm white light and achieved high Ra (Ra = 94, 96.6, 92.7) and low correlated color temperature (CCT = 3486, 3430, 3788 K), indicating that the prepared solid solution phosphors can be used as candidate materials for WLED lighting.

Energy transfer and tunable emission in BaSrGd4O8:Bi3+,Eu3+ phosphors for warm WLED.

In this work, a series of BaSrGd4O8:xBi3+ blue phosphors was synthesized employing the high-temperature solid-state method. Phase purity of the samples was verified by X-ray diffraction and Rietveld refinement. Time-resolved photoluminescence spectra revealed the existence of two distinct Bi sites. Subsequent optimization of dopant types and doping levels in the batch led to an almost twofold increase in quantum efficiency. The introduction of Eu3+ into the phosphors facilitated the construction of an energy transfer pathway. As the concentration of Eu3+ was increased, the emission color changed from blue to purple and finally to red. In addition, the thermal stability and potential applications of the phosphors were extensively investigated. Finally, two WLED devices were successfully fabricated with color rendering indices of 96.27 and 92.18, and correlated color temperatures of 5198 and 2475 K. This underscores the prospective application of these phosphors in the field of high-quality warm WLEDs.

An efficient blue-excitable broadband Y3ScAl4O12:Ce3+ garnet phosphor for WLEDs.

Most commercial phosphor-converted white light-emitting diodes (pc-WLEDs) are manufactured with blue LED chips and yellow-emitting Y3Al5O12:Ce3+ (YAG:Ce3+) garnet phosphor, but the lack of blue-green light in the spectrum results in a low color rendering index (CRI). In this paper, we synthesized Y3ScAl4O12:Ce3+ (YSAG:Ce3+) by replacing Al3+ in YAG:Ce3+ with Sc3+. The introduction of Sc3+ with a larger ionic radius through a cation substitution strategy causes lattice expansion, elongation of the Y-O bond, and ultimately a decrease in Ce3+ 5d level crystal field splitting. As a consequence, the emission spectrum undergoes a blue-shift of 10 nm. Furthermore, the YSAG:Ce3+ phosphor exhibits good thermal stability, and its emission intensity at 423 K is about 58% of that at 303 K. Moreover, the analysis of Eu3+ emission spectra demonstrates that the introduction of Sc3+ resulted in a slight reduction of the dodecahedral lattice symmetry. YSAG:Ce3+ effectively compensates for the lack of the blue-green region, and WLEDs with high color rendering index (90.1), low color temperature (4566 K) and high luminous efficiency (133.59 lm W-1) were prepared using the combination of YSAG:0.08Ce3+, CaAlSiN3:Eu2+ and 450 nm blue chips. These findings indicate that YSAG:Ce3+ garnet phosphor has potential to be used in high quality WLEDs.

Efficient and zero thermal quenching Sm3+-activated Li2LaTiTaO7 phosphor for white LEDs.

In this work, we prepared a new orange-red phosphor Li2La1-xTiTaO7:xSm3+ (abbreviated as LLTT:Sm3+) for white light-emitting diodes (w-LEDs). Its crystal structure, microstructure, photoluminescence characteristics, luminescence lifetime and thermal quenching properties were studied in depth. The LLTT:Sm3+ phosphor shows four intense emission peaks at 563, 597, 643, and 706 nm when excited at 407 nm. Thermal quenching is caused by the dipole-quadrupole (d-q) interaction of Sm3+ ions, and the optimum doping concentration of Sm3+ is x = 0.05. Meanwhile, the LLTT:0.05Sm3+ phosphor has a high overall quantum yield (QY = 59.65%) and almost no thermal quenching. The emission intensity at 423 K is 101.5% of the initial value at 298 K, while the CIE chromaticity coordinates barely change as the temperature rises. The fabricated white LED device exhibits excellent CRI and CCT values of 90.4 and 5043 K, respectively. These findings demonstrate that the LLTT:Sm3+ phosphor has promise in w-LED applications.

Lanthanide-doped Na2MgScF7 exhibiting downshifting and upconversion emissions for multicolor anti-counterfeiting.

Na2MgScF7 (NMSF) was experimentally obtained for the first time by combining hydrothermal and high-temperature solid-state reactions. X-ray powder diffraction (XRD) combined with Rietveld refinement confirms that NMSF is crystallized in the space group Imma with the cell parameters a = 10.40860(18), b = 7.32804(12) and c = 7.52879(11) Å, α = ß = γ = 90° and V = 574.256(24) Å3. Through doping with Tb3+ or Eu3+ ions, downshifting yellow-green or red emission could be achieved in NMSF-based phosphors, respectively. Upconversion emission could also be designed by doping with Yb3+-Er3+, Yb3+-Tm3+, Yb3+-Ho3+ or Er3+. Moreover, the NMSF:Er3+ phosphor exhibited green upconversion emission upon excitation at 980 nm, and it exhibited red emission upon excitation at 1532 nm. Finally, recognizable patterns were obtained under excitation at 254, 365 and 980 nm, indicating that the as-prepared phosphors can be applied to multicolor anti-counterfeiting. Moreover, our synthesis strategy opens up new avenues for the synthesis of novel fluorides.

Achieving High Quantum Efficiency Broadband NIR Mg4 Ta2 O9 :Cr3+ Phosphor Through Lithium-Ion Compensation.

Ultra-efficient broadband near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) are urgently needed to improve the detection sensitivity and spatial resolution of current smart NIR spectroscopy-based techniques. Nonetheless, the performance of NIR pc-LED has severely limited owing to the external quantum efficiency (EQE) bottleneck of NIR light-emitting materials. Herein, a blue LED excitable Cr3+ -doped tetramagnesium ditantalate (Mg4 Ta2 O9 , MT) phosphor is advantageously modified through lithium ion as a key efficient broadband NIR emitter to achieve high optical output power of the NIR light source. The emission spectrum encompasses the 700-1300 nm electromagnetic spectrum of first biological window (λmax  = 842 nm) with a full-width at half-maximum (FWHM) of ≈2280 cm-1 (≈167 nm), and achieves a record EQE of 61.25% detected at 450 nm excitation through Li-ion compensation. A prototype NIR pc-LED is fabricated with MT:Cr3+ , Li+ to evaluate its potential practical application, which reveals an NIR output power of 53.22 mW at a driving current of 100 mA, and a photoelectric conversion efficiency of 25.09% at 10 mA. This work provides an ultra-efficient broadband NIR luminescent material, which shows great promise in practical applications and presents a novel option for the next-generation high-power compact NIR light sources.

Double Perovskite Mn4+-Doped La2CaSnO6/La2MgSnO6 Phosphor for Near-Ultraviolet Light Excited W-LEDs and Plant Growth.

Non-rare earth doped oxide phosphors with far-red emission have become one of the hot spots of current research due to their low price and excellent physicochemical stability as the red component in white light-emitting diodes (W-LEDs) and plant growth. Herein, we report novel Mn4+-doped La2CaSnO6 and La2MgSnO6 phosphors by high-temperature solid-phase synthesis and analyzed their crystal structures by XRD and Rietveld refinement. Their excitation spectra consist of two distinct excitation bands with the dominant excitation range from 250 to 450 nm, indicating that they possess strong absorption of near-ultraviolet light. Their emission is located around 693 and 708 nm, respectively, and can be absorbed by the photosensitive pigments Pr and Pfr, proving their great potential for plant growth. Finally, the prepared samples were coated with 365 nm UV chips to fabricate far-red LEDs and W-LEDs with low correlation color temperature (CCT = 4958 K/5275 K) and high color rendering index (Ra = 96.4/96.6). Our results indicate that La2CaSnO6:Mn4+ and La2MgSnO6:Mn4+ red phosphors could be used as candidate materials for W-LED lighting and plant growth.

A Color-tunable Nitride Phosphor for Near-Ultraviolet Excitation of White Light-emitting Diodes.

Due to the diversity of structure and composition and the unique coordination environment, nitride materials enable the doped activator ions to possess compelling luminescence characteristics, such as rich emission colors, favorable stability and tunable emission spectra. Here, novel SrLuSi4 N7 :Ce3+ ,Tb3+ nitride phosphors were successfully synthesized by a modified carbothermal reduction and nitridation method at atmospheric pressure. SrLuSi4 N7 (SLSN) belongs to hexagonal symmetry, with space group P63 mc, and its crystal structure is composed of the basic building block with corner-sharing [SiN4 ] tetrahedron. Under 365 nm excitation, SLSN:Ce3+ exhibits a broad emission band peaking at 450 nm with a full width at half-maximum (FWHM) of 92 nm and the most forceful intensity obtained at the Ce3+ concentration amount of 0.04. On the basis of the efficient energy transfer, SLSN:Ce3+ ,Tb3+ exhibits color-tunable emission from blue (450 nm) to green (545 nm). Our results indicate that SLSN nitride phosphor is a promising candidate for near-ultraviolet (n-UV) based white LEDs.

Broadband Near-Infrared-Emitting Phosphors with Suppressed Concentration Quenching in a Two-Dimensional Structure.

For inorganic luminescent materials with activators, the energy yield is usually observed to decrease with an increase in activator concentration, which is known as the concentration quenching effect. To inhibit this phenomenon, a common strategy is to increase the distance between activators. Most previous reports have focused on the three-dimensional crystal lattice, and there have been few reports about two-dimensional layered structure. Herein, we synthesized a novel Cr3+-activated near-infrared (NIR) phosphor Li2Sr2Al(PO4)3 (LSAPO) with layered structure, and in such a two-dimensional structure, we proved experimentally that the concentration quenching was suppressed. Under 460 nm excitation, LSAPO:Cr3+ gave a broad NIR emission band (700-1200 nm) centered at 823 nm with a full width at half-maximum (fwhm) of 178 nm and a broad absorption band, indicating its potential application in NIR spectroscopy. Moreover, by codoping Cr3+ and Yb3+ ions, we further widened the emission bandwidth to ∼230 nm of fwhm, the internal quantum efficiency increased from 54% to 61%, and the thermal stability was improved. The fabricated NIR device with a LSAPO:Cr3+,Yb3+ phosphor coupled with blue chips can be applied in night-vision technologies and medical fields.

Highly thermally stable Cr3+ and Yb3+ codoped Gd2GaSbO7 phosphors for broadband near-infrared applications.

Gd2GaSbO7:Cr3+,Yb3+ phosphors with efficient broadband NIR emission were prepared by a solid-state reaction. Under the excitation of 448 nm, the Gd2GaSbO7:Cr3+ (GGS:Cr3+) phosphor exhibits a broadband NIR emission band centered at approximately 770 nm with a full width at half maximum (FWHM) of 160 nm. In addition, Yb3+ codoping can distinctly improve the photoluminescence properties of the GGS:Cr3+ phosphor, leading to broadening of the FWHM and greatly enhancing the thermal stability of the phosphor. Moreover, the energy conversion process of Cr3+ → Yb3+ ions was analyzed in detail, demonstrating that the energy transfer mechanism conformed to electric dipole-dipole interaction. The NIR pc-LEDs assembled with the GGS:Cr3+ phosphor and blue LED chips possessed a maximum NIR output power of ∼21 mW at 100 mA driving current, indicating promising applications of the synthesized phosphor in NIR pc-LEDs.

Synthesis, Characterization, and Catalytic Study of Amine-Bridged Bis(phenolato) Co(II) and Co(II/III)-M(I) Complexes (M = K or Na).

Co(II) complexes 1-3 bearing amine-bridged bis(phenolato) complexes have been synthesized through reactions of bis(phenols) with CoCl2 or Co(OAc)2. Oxidation of the Co(II) complex with air resulted in partial oxidation, generating mixed valence Co(II/III) complexes 4 and 5. In addition, due to the presence of alkali compounds (KOAc and NaOMe), 4 and 5 formed as Co-alkali metal heterometallic complexes, which are the first example of mixed valence Co(II/III)-M(I) (M = K or Na) complexes. Complexes 1-5 showed good activity in the cycloaddition of epoxides and CO2 under atmospheric pressure, generating cyclic carbonates in 40-99% yields. Co(II/III)-Na(I) complex 5 performed better in reactions of bulkier substrates, underlining the enhanced activity of mixed valence Co-alkali metal heterometallic complexes. On the contrary, complex 5 showed limited activity in copolymerization of epoxide and CO2.

Novel SrGd2Al2O7:Mn4+, Nd3+, and Yb3+ phosphors for c-Si solar cells.

Novel single-doped and codoped SrGd2Al2O7-based (SGA) phosphors with tunable emission were synthesized via the solid-state reaction approach. The optimal SGA:0.0008Mn4+ phosphor presents an emission band peaking at 709 nm and shows great red luminescence properties. With the incorporation of Nd3+/Yb3+ into SGA:0.0008Mn4+, an efficient energy transfer Mn4+→ Nd3+/Yb3+ was observed. When Nd3+ and Yb3+ were codoped into SGA:0.0008Mn4+, an energy transfer mechanism from Mn4+ to Nd3+ to Yb3+ was found on the basis of the energy transfer mediation of Nd3+ connecting the Mn4+ and Yb3+ luminescent centers. It results in a strong near-infrared emission in the spectral region of high response of c-Si solar cells, which suggests a potential approach to improve the energy conversion efficiency of c-Si solar cells. The findings offer a novel route to design new down-conversion luminescent materials for the c-Si solar cells.

Heterobimetallic rare earth metal-zinc catalysts for reactions of epoxides and CO2 under ambient conditions.

Four homodinuclear rare earth metal (RE) complexes 1-4 bearing a multidentate diglycolamine-bridged bis(phenolate) ligand were synthesized. In addition, seven heterobimetallic RE-Zn complexes 5-11 were prepared through a one-pot strategy. In these heterobimetallic complexes, two RE centers are bridged by either Zn(OAc)2 or Zn(OBn)2 moieties. All complexes were characterized by single crystal X-ray diffraction, elemental analysis, IR spectroscopy, and multinuclear NMR spectroscopy (in the case of diamagnetic complexes 1, 4, 7 and 11). Moreover, the multi-nuclear structures of complexes 4 and 11 in solution were also studied by 1H DOSY spectroscopy. These complexes were applied in catalyzing the coupling reaction of carbon dioxide (CO2) with epoxides. Zn(OAc)2- and Zn(OBn)2-bridged heterobimetallic complexes showed comparable catalytic activities under ambient conditions and were more active than monometallic RE complexes. Significant synergistic effect in heterobimetallic complexes is observed. Mono-substituted epoxides were converted into cyclic carbonates under 1 atm CO2 at 25 °C in 88-96% yields, whereas di-substituted epoxides reacted under 1 atm CO2 at higher temperatures in 40-80% yields.