A Configurationally Stable Helical Indenofluorene.

We report the synthesis and study of the optoelectronic, magnetic, and chiroptical properties of a helically chiral diradicaloid based on dibenzoindeno[2,1-c]fluorene. The molecule shows a small HOMO-LUMO gap and a moderate singlet-triplet gap, which agrees with the results of DFT calculations. The helical structure of the compound, confirmed by X-ray diffraction, is configurationally stable, which allows the isolation of both enantiomers and the evaluation of the chiroptical properties (ECD).

Tuning Reprocessing Temperature of Aliphatic Polyurethane Networks by Alkoxyamine Selection.

Recent studies have shown that the largest employed thermoset family, polyurethanes (PUs), has great potential to be reprocessed due to the dynamic behavior of carbamate linkage. However, it requires high temperatures, especially in the case of aliphatic PUs, which causes side reactions besides the desired exchange reaction. To facilitate the reprocessing of aliphatic PUs, in this work, we have explored the dynamic potential of alkoxyamine bonds in PU networks to facilitate the reprocessing under mild conditions considering their fast recombination ability. Taking advantage of the structural effect of the nitroxide and alkyl radicals on the dissociation energy, two different alkoxyamine-based diols have been designed and synthesized to generate PU networks. Our study shows that replacing 50 mol % of a nondynamic diol chain extender with these dynamic blocks boosts the relaxation times of the networks, enabling reprocessing at temperatures as low as 80 °C.

Effect of the heteroatom on the magnetic and luminescence properties of hybrid lanthanide-substituted Keggin-type polyoxometalates.

Replacement of the heteroatom from Si to Ge has a strong influence on the luminescence properties of a series of hybrid, sandwich-type K5[Ln(α-GeW11O39)(C20H22Br2N2O4)]·14H2O (1Ge-Ln, Ln = Sm to Lu) anions. Interestingly, the Gd and Yb derivatives retain their ability to display slow relaxation of magnetisation.

Crystal-to-crystal polymerisation of monosubstituted [PW11O39Cu(H2O)]5- Keggin-type anions.

The reaction between neutral bis(picolinate)copper(II) complexes and copper(II)-monosubstituted Keggin-type phosphotungstate anions formed in situ leads to the formation of the hybrid [C(NH2)3]10[{PW11O39Cu(H2O)}2{Cu(pic)2}]·10H2O compound (1, pic = picolinate) in the presence of structure-directing guanidinium cations. Single-crystal X-ray diffraction studies demonstrate that 1 contains dimeric {PW11O39Cu(H2O)}2{Cu(pic)2} molecular species constituted by two Keggin-type anions linked by one {Cu(pic)2} octahedral complex through axial coordination to their terminal oxygen atoms. The extensive hydrogen-bonding network established by guanidium cations and Keggin clusters plays a key role in retaining the crystallinity of the system throughout dehydration to allow a single-crystal-to-single-crystal (SCSC) transformation into the anhydrous [C(NH2)3]10[{PW11O39Cu}2{Cu(pic)2}] (2a) at 170 °C. Structural modifications involve the re-orientation, shifting in ca. 1.5 Å and condensation of all the {PW11O39Cu} units to result in {PW11O39Cu}n chains in an unprecedented solid-state polymerisation. This phase transition also implies the cleavage of Cu-O bonds induced by the rotation and translation of Keggin-type anions, in such a way that hybrid dimeric units in 1 are dismantled and {Cu(pic)2} complexes become square planar. The irreversibility of the phase transition has been confirmed by combined thermal and diffractometric analyses, which evidence that the anhydrous phase adsorbs only one water molecule per cluster to become the [C(NH2)3]10[{PW11O39Cu}2{Cu(pic)2}]·2H2O (2h) hydrated derivative without any significant alteration in its cell parameters, nor in its crystalline structure. Phase transformations have been monitored by electron paramagnetic resonance spectroscopy.

Direct Evidence of the Effect of Water Molecules Position in the Spectroscopy, Dynamics, and Lighting Performance of an Eco-Friendly Mn-Based Organic-Inorganic Metal Halide Material for High-Performance LEDs and Solvent Vapor Sensing.

Luminescent Mn(II)-based organic-inorganic hybrid halides have drawn attention as potential materials for sensing and photonics applications. Here, the synthesis and characterization of methylammonium (MA) manganese bromide ((MA)nBrxMn(H2O)2, (n = 1, 4 and x = 3, 6)) with different stoichiometries of the organic cation and inorganic counterpart, are reported. While the Mn2+ centers have an octahedral conformation, the two coordinating water molecules are found either in cis (1) or in trans (2) positions. The photophysical behavior of 1 reflects the luminescence of Mn2+ in an octahedral environment. Although Mn2+ in 2 also has octahedral coordination, at room temperature dual emission bands at ≈530 and ≈660 nm are observed, explained in terms of emission from Mn2+ in tetragonally compressed octahedra and self-trapped excitons (STEs), respectively. Above the room temperature, 2 shows quasi-tetrahedral behavior with intense green emission, while at temperatures below 140 K, another STE band emerges at 570 nm. Time-resolved experiments (77-360 K) provide a clear picture of the excited dynamics. 2 shows rising components due to STEs formation equilibrated at room temperature with their precursors. Finally, the potential of these materials for the fabrication of color-tunable down-converted light-emitting diode (LED) and for detecting polar solvent vapors is shown.

Fast Visible-Light 3D Printing of Conductive PEDOT:PSS Hydrogels.

Functional inks for light-based 3D printing are actively being searched for being able to exploit all the potentialities of additive manufacturing. Herein, a fast visible-light photopolymerization process is showed of conductive PEDOT:PSS hydrogels. For this purpose, a new Type II photoinitiator system (PIS) based on riboflavin (Rf), triethanolamine (TEA), and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is investigated for the visible light photopolymerization of acrylic monomers. PEDOT:PSS has a dual role by accelerating the photoinitiation process and providing conductivity to the obtained hydrogels. Using this PIS, full monomer conversion is achieved in less than 2 min using visible light. First, the PIS mechanism is studied, proposing that electron transfer between the triplet excited state of the dye (3 Rf*) and the amine (TEA) is catalyzed by PEDOT:PSS. Second, a series of poly(2-hydroxyethyl acrylate)/PEDOT:PSS hydrogels with different compositions are obtained by photopolymerization. The presence of PEDOT:PSS negatively influences the swelling properties of hydrogels, but significantly increases its mechanical modulus and electrical properties. The new PIS is also tested for 3D printing in a commercially available Digital Light Processing (DLP) 3D printer (405 nm wavelength), obtaining high resolution and 500 µm hole size conductive scaffolds.

Bio-based ether solvent and ionic liquid electrolyte for sustainable sodium-air batteries.

Sodium-air batteries (SABs) are receiving considerable attention for the development of next generation battery alternatives due to their high theoretical energy density (up to 1105 W h kg-1). However, most of the studies on this technology are still based on organic solvents; in particular, diglyme, which is highly flammable and toxic for the unborn child. To overcome these safety issues, this research investigates the first use of a branched ether solvent 1,2,3-trimethoxypropane (TMP) as an alternative electrolyte to diglyme for SABs. Through this work, the reactivity of the central tertiary carbon in TMP towards bare sodium metal was identified, while the addition of N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C4mpyr][TFSI]) as a co-solvent proved to be an effective strategy to limit the reactivity. Moreover, a Na-ß-alumina disk was employed for anode protection, to separate the TMP-based electrolyte from the sodium metal. The new cell design resulted in improved cell performance: discharge capacities of up to 1.92 and 2.31 mA h cm-2 were achieved for the 16.6 mol% NaTFSI in TMP and 16.6 mol% NaTFSI in TMP/[C4mpyr][TFSI] compositions, respectively. By means of SEM, Raman and 23Na NMR techniques, NaO2 cubes were identified to be the major discharge product for both electrolyte compositions. Moreover, the hybrid electrolyte was shown to hinder the formation of side-products during discharge - the ratio of NaO2 to side-products in the hybrid electrolyte was 2.4 compared with 0.8 for the TMP-based electrolyte - and a different charge mechanism for the dissolution of NaO2 cubes for each electrolyte was observed. The findings of this work demonstrate the high potential of TMP as a base solvent for SABs, and the importance of careful electrolyte composition design in order to step towards greener and less toxic batteries.

H(N3)dap (Hdap = 2,6-Diaminopurine) Recognition by Cu2(EGTA): Structure, Physical Properties, and Density Functional Theory Calculations of [Cu4(µ-EGTA)2(µ-H(N3)dap)2(H2O)2]·7H2O.

Reactions in water between the Cu2(µ-EGTA) chelate (EGTA = ethylene-bis(oxyethyleneimino)tetraacetate(4-) ion) and Hdap in molar ratios 1:1 and 1:2 yield only blue crystals of the ternary compound [Cu4(µ-EGTA)2(µ-H(N3)dap)2(H2O)2]·7H2O (1), which has been studied via single-crystal X-ray diffraction and various physical methods (thermal stability, spectral and magnetic properties), as well as DFT theoretical calculations. In the crystal, uncoordinated water is disordered. The tetranuclear complex molecule also has some irrelevant disorder in an EGTA-ethylene moiety. In the complex molecule, both bridging organic molecules act as binucleating ligands. There are two distorted five- and two six-coordinated Cu(II) centers. Each half of EGTA acts as a tripodal tetradentate Cu(II) chelator, with a mer-NO2 + O(ether, distal) conformation. Hdap exhibits the tautomer H(N3)dap, with the dissociable H-atom on its less basic N-heterocyclic atom. These features favor the efficient cooperation between Cu-N7 or Cu-N9 bonds with appropriate O-EGTA atoms, as N6-H···O or N3-H···O interligand interactions, respectively. The bridging role of both organics determines the tetranuclear dimensionality of the complex. In this crystal, such molecules associate in zig-zag chains built by alternating π-π interactions between the five- or six-atom rings of Hdap ligands of adjacent molecules. DFT theoretical calculations (using two different theoretical models and characterized by the quantum theory of "atoms in molecules") reveal the importance of these π-π interactions between Hdap ligands, as well as those corresponding to the referred hydrogen bonds in the contributed tetranuclear molecule.

Molecular Tailoring of Pyridine Core-Based Hole Selective Layer for Lead Free Double Perovskite Solar Cells Fabrication.

To solve the toxicity issues related to lead-based halide perovskite solar cells, the lead-free double halide perovskite Cs2AgBiBr6 is proposed. However, reduced rate of charge transfer in double perovskites affects optoelectronic performance. We designed a series of pyridine-based small molecules with four different arms attached to the pyridine core as hole-selective materials by using interface engineering. We quantified how arm modulation affects the structure-property-device performance relationship. Electrical, structural, and spectroscopic investigations show that the N3,N3,N6,N6-tetrakis(4-methoxyphenyl)-9H-carbazole-3,6-diamine arm's robust association with the pyridine core results in an efficient hole extraction for PyDAnCBZ due to higher spin density close to the pyridine core. The solar cells fabricated using Cs2AgBiBr6 as a light harvester and PyDAnCBZ as the hole selective layer measured an unprecedented 2.9% power conversion efficiency. Our computed road map suggests achieving ∼5% efficiency through fine-tuning of Cs2AgBiBr6. Our findings reveal the principles for designing small molecules for electro-optical applications as well as a synergistic route to develop inorganic lead-free perovskite materials for solar applications.

Preparation of Selenium-Based Drug-Modified Polymeric Ligand-Functionalised Fe3O4 Nanoparticles as Multimodal Drug Carrier and Magnetic Hyperthermia Inductor.

In recent years, much effort has been invested into developing multifunctional drug delivery systems to overcome the drawbacks of conventional carriers. Magnetic nanoparticles are not generally used as carriers but can be functionalised with several different biomolecules and their size can be tailored to present a hyperthermia response, allowing for the design of multifunctional systems which can be active in therapies. In this work, we have designed a drug carrier nanosystem based on Fe3O4 nanoparticles with large heating power and 4-amino-2-pentylselenoquinazoline as an attached drug that exhibits oxidative properties and high selectivity against a variety of cancer malignant cells. For this propose, two samples composed of homogeneous Fe3O4 nanoparticles (NPs) with different sizes, shapes, and magnetic properties have been synthesised and characterised. The surface modification of the prepared Fe3O4 nanoparticles has been developed using copolymers composed of poly(ethylene-alt-maleic anhydride), dodecylamine, polyethylene glycol and the drug 4-amino-2-pentylselenoquinazoline. The obtained nanosystems were properly characterised. Their in vitro efficacy in colon cancer cells and as magnetic hyperthermia inductors was analysed, thereby leaving the door open for their potential application as multimodal agents.

Consecutive Single-Crystal-to-Single-Crystal Isomerization of Novel Octamolybdate Anions within a Microporous Hybrid Framework with Robust Water Sorption Properties.

The 3D hybrid framework [{Cu(cyclam)}3 (κ-Mo8 O27 )] ⋅ 14H2 O (1) (cyclam=1,4,8,11-tetraazacyclotetradecane) undergoes sequential single-crystal-to-single-crystal transformations upon heating to afford two different anhydrous phases (2 a and 3 a). These transitions modify the framework dimensionality and enable the isomerization of κ-octamolybdate (κ-Mo8 ) anions into λ (2 a) and µ (3 a) forms through metal migration. Hydration of 3 a involves condensation of one water molecule to the cluster to afford the γ-Mo8 isomer in 4, which dehydrates back into 3 a through the 6 a intermediate. In contrast, 2 a reversibly hydrates to form 5, exhibiting the same Mo8 cluster as that of 1. It is remarkable that three of the Mo8 clusters (κ, λ and µ) are new and that up to three different microporous phases can be isolated from 1 (2 a, 3 a, and 6 a). Water vapor sorption analyses show high recyclability and the highest uptake values for POM-based systems. The isotherms display an abrupt step at low humidity level desirable for humidity control devices or water harvesting in drylands.

The Effects of Mono- and Bivalent Linear Alkyl Interlayer Spacers on the Photobehavior of Mn(II)-Based Perovskites.

Mn(II)-based perovskite materials are being intensively explored for lighting applications; understanding the role of ligands regarding their photobehavior is fundamental for their development. Herein, we report on two Mn (II) bromide perovskites using monovalent (perovskite 1, P1) and bivalent (perovskite 2, P2) alkyl interlayer spacers. The perovskites were characterized with powder X-ray diffraction (PXRD), electron spin paramagnetic resonance (EPR), steady-state, and time-resolved emission spectroscopy. The EPR experiments suggest octahedral coordination in P1 and tetrahedral coordination for P2, while the PXRD results demonstrate the presence of a hydrated phase in P2 when exposed to ambient conditions. P1 exhibits an orange-red emission, while P2 shows a green photoluminescence, as a result of the different types of coordination of Mn(II) ions. Furthermore, the P2 photoluminescence quantum yield (26%) is significantly higher than that of P1 (3.6 %), which we explain in terms of different electron-phonon couplings and Mn-Mn interactions. The encapsulation of both perovskites into a PMMA film largely increases their stability against moisture, being more than 1000 h for P2. Upon increasing the temperature, the emission intensity of both perovskites decreases without a significant shift in the emission spectrum, which is explained in terms of an increase in the electron-phonon interactions. The photoluminescence decays fit two components in the microsecond regime-the shortest lifetime for hydrated phases and the longest one for non-hydrated phases. Our findings provide insights into the effects of linear mono- and bivalent organic interlayer spacer cations on the photophysics of these kinds of Mn (II)-based perovskites. The results will help in better designs of Mn(II)-perovskites, to increase their lighting performance.

Amorphous FeCoCrSiB Ribbons with Tailored Anisotropy for the Development of Magnetic Elements for High Frequency Applications.

The ferromagnetic resonance (FMR) in the frequency range of 0.5 to 12.5 GHz has been investigated as a function of external magnetic field for rapidly quenched Fe3Co67Cr3Si15B12 amorphous ribbons with different features of the effective magnetic anisotropy. Three states of the ribbons were considered: as-quenched without any treatment; after relaxation annealing without stress at the temperature of 350 °C during 1 h; and after annealing under specific stress of 230 MPa at the temperature of 350 °C during 1 h. For FMR measurements, we adapted a technique previously proposed and tested for the case of microwires. Here, amorphous ribbons were studied using the sample holder based on a commercial SMA connector. On the basis of the measurements of the reflection coefficient S11, the total impedance including its real and imaginary components was determined to be in the frequency range of 0.5 to 12.5 GHz. In order to confirm the validity of the proposed technique, FMR was also measured by the certified cavity perturbation technique using a commercial Bruker spectrometer operating at X-band frequency of 9.39 GHz. As part of the characterization of the ribbons used for microwave measurements, comparative analysis was performed of X-ray diffraction, optical microscopy, transmission electron microscopy, inductive magnetic hysteresis loops, vibrating sample magnetometry, magneto-optical Kerr effect (including magnetic domains) and magnetoimpedance data for of all samples.

Fast Visible-Light Photopolymerization in the Presence of Multiwalled Carbon Nanotubes: Toward 3D Printing Conducting Nanocomposites.

A new photoinitiator system (PIS) based on riboflavin (Rf), triethanolamine, and multiwalled carbon nanobutes (MWCNTs) is presented for visible-light-induced photopolymerization of acrylic monomers. Using this PIS, photopolymerization of acrylamide and other acrylic monomers was quantitative in seconds. The intervention mechanism of CNTs in the PIS was studied deeply, proposing a surface interaction of MWCNTs with Rf which favors the radical generation and the initiation step. As a result, polyacrylamide/MWCNT hydrogel nanocomposites could be obtained with varying amounts of CNTs showing excellent mechanical, thermal, and electrical properties. The presence of the MWCNTs negatively influences the swelling properties of the hydrogel but significantly improves its mechanical properties (Young modulus values) and electric conductivity. The new PIS was tested for 3D printing in a LCD 3D printer. Due to the fast polymerizations, 3D-printed objects based on the conductive polyacrylamide/CNT nanocomposites could be manufactured in minutes.

Towards the design of contrast-enhanced agents: systematic Ga3+ doping on magnetite nanoparticles.

The main objective of the preparation of the Fe3-xGaxO4 (0.14 ≤ x ≤ 1.35) system was to further the knowledge of the magnetic response of Ga3+-doped magnetite for application as MRI contrast agents. With this purpose, monodisperse nanoparticles between 7 and 10 nm with different amounts of gallium were prepared from an optimized protocol based on thermal decomposition of metallo-organic precursors. Thorough characterization of the sample was conducted in order to understand the influence of gallium doping on the structural, morphological and magnetic properties of the Fe3-xGaxO4 system. X-ray diffraction and X-ray absorption near-edge structure measurements have proved the progressive incorporation of Ga in the spinel structure, with different occupations in both tetrahedral and octahedral sites. Magnetization measurements as a function of field temperature have shown a clear dependence of magnetic saturation on the gallium content, reaching an Ms value of 110 Am2 kg-1 at 5 K for x = 0.14 (significantly higher than bulk magnetite) and considerably decreasing for amounts above x = 0.57 of gallium. For this reason, nanoparticles with moderate Ga quantities were water-transferred by coating them with the amphiphilic polymer PMAO to further analyse their biomedical potential. Cytotoxicity assays have demonstrated that Fe3-xGaxO4@PMAO formulations with x ≤ 0.57, which are the ones with better magnetic response, are not toxic for cells. Finally, the effect of gallium doping on relaxivities has been analysed by measuring longitudinal (T1-1) and transverse (T1-1) proton relaxation rates at 1.4 T revealing that nanoparticles with x = 0.14 Ga3+ content present remarkable T2 contrast and the nanoparticles with x = 0.26 have great potential to act as dual T1-T2 contrast agents.

Leverage of Pyridine Isomer on Phenothiazine Core: Organic Semiconductors as Selective Layers in Perovskite Solar Cells.

To drive the development of perovskite solar cells (PSCs), hole-transporting materials are imperative. In this context, pyridine derivatives are being probed as small molecules-based hole-transporting materials due to their Lewis base and electron-deficient unit. Herein, we focused our investigation on pyridine isomer molecules 4,4'-(10-(pyridin-x-yl)-10H-phenothiazine-3,7-diyl)bis(N,N-bis(4-methoxyphenyl)aniline) (x = 2, 3, or 4), in which the pyridine nitrogen heteroatom is located at the 2, 3, and 4 positions, named as 2PyPTPDAn, 3PyPTPDAn, and 4PyPTPDAn, respectively. We decipher the structure-properties-device performance relationship impacted by the different N-atom positions in pyridine. In the case of 3PyPTPDAn, the partial orbital overlap between highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) favors the generation of neutral excitons and hole transport, as well as improves the film-formation ability, and this induces efficient hole extraction as compared to their 2,4 analogues. The solar cells fabricated with 3PyPTPDAn gave on-par photovoltaic performance as that of typical Spiro-OMeTAD, and higher performance than those of 2PyPTPDAn and 4PyPTPDAn. The hydrophobicity and homogeneous film properties of 3PyPTPDAn add merits to the stability. This work emphasizes the guidelines to develop small molecules for organic solar cells, organic light-emitting diodes, and thermally activated delayed fluorescence.

Slow Magnetic Relaxation and Luminescent Properties of Mononuclear Lanthanide-Substituted Keggin-Type Polyoxotungstates with Compartmental Organic Ligands.

The reaction of mid to late lanthanide ions with the N,N'-dimethyl-N,N'-bis(2-hydroxy-3-formyl-5-bromobenzyl)ethylene-diamine organic ligand and monolacunary Keggin type [α-SiW11O39]8- anion affords a series of isostructural compounds, namely, K5[LnIII(α-SiW11O39)(C20H22Br2N2O4)]·14H2O (1-Ln, Ln = Sm to Lu). The molecular structure of these sandwich-type complexes is formed by the LnIII ion in a biaugmented trigonal prismatic geometry, which occupies the external O4 site of the organic ligand and the vacant site of the lacunary polyoxometalate (POM) unit. The empty N2O2 coordination site of the organic ligand allows its unprecedented folding, which displays a relative perpendicular arrangement of aromatic groups. Weak Br···Br and π-π interactions established between adjacent molecular units govern the crystal packing, which results in the formation of assemblies containing six hybrid species assembled in a chairlike conformation. 1-Gd and 1-Yb display slow relaxation of the magnetization after the application of an external magnetic field with maxima in the out-of-phase magnetic susceptibility plots below ∼5-6 K, which is ascribed to the presence of various relaxation mechanisms. Moreover, photoluminescent emission is sensitized for 1-Sm and 1-Eu in the visible region and 1-Er and 1-Yb in the NIR. In contrast, the quenching of metal-centered luminescence in the 1-Tb derivative has been attributed to the out-of-pocket coordination mode of the lanthanide center within the POM fragment. It is demonstrated that the 1-Yb dual magneto-luminescent material represents the first lanthanide-containing POM reported to date with simultaneous slow magnetic relaxation and NIR emission. Solution stability of the hybrid molecular species in water is also confirmed by ESI-mass spectrometry experiments carried out for 1-Tb and 1-Tm.

Finite Element Modeling of Hot Rolling of 1075 Carbon Steel Process with Variable Cross Section.

Currently, it is common to use steel poles for applications in livestock and agriculture. In this work, finite element analysis of five hot rolling passes for the manufacture of farm poles using 1075 carbon steels from recycled railway material was developed. The steel industry in Mexico imports products from other countries or from companies specialized in metallurgy at an excessive cost. To be more competitive and save costs, companies seek the reutilization of existing resources such as the railway 1075 steel, which has good mechanical properties. SFTC DEFORM-3D software was used to model five hot rolling passes considering a variable cross section railway profile. The effect of rolling speed and temperature were considered to analyze flow behavior. Rolling loads were also determined.

Single-Crystal-to-Single-Crystal Cluster Transformation in a Microporous Molybdoarsenate(V)-Metalorganic Framework.

The hybrid compound [Cu(cyclam)(H2O)2]0.5[{Cu(cyclam)}1.5{B-H2As2Mo6O26(H2O)}]·9H2O (1) (cyclam = 1,4,8,11-tetraazacyclotetradecane) was synthesized in aqueous solution by reacting the {Cu(cyclam)}2+ complex with a mixture of heptamolybdate and an arsenate(V) source. Crystal packing of 1 exhibits a supramolecular open-framework built of discrete covalent molybdoarsenate/metalorganic units and additional [Cu(cyclam)(H2O)2]2+ cations, the stacking of which generates squarelike channels parallel to the z axis with an approximate cross section of 10 × 11 Å2 where all the hydration water molecules are hosted. Thermal evacuation of solvent molecules yields a new anhydrous crystalline phase, but compound 1 does not preserve its single-crystalline nature upon heating. However, when crystals are dehydrated under vacuum, they undergo a structural transformation that proceeds via a single-crystal-to-single-crystal pathway, leading to the anhydrous phase [{Cu(cyclam)}2(A-H2As2Mo6O26)] (2). Total dehydration results in important modifications within the inorganic cluster skeleton which reveals an unprecedented solid-state B to A isomerization of the polyoxoanion. This transition also involves changes in the CuII bonding scheme that lead to covalent cluster/metalorganic layers by retaining the open-framework nature of 1. Compound 2 adsorbs ambient moisture upon air exposure, but it does not revert back to 1, and the hydrated phase [{Cu(cyclam)}2(A-H2As2Mo6O26)]·6H2O (2h) is obtained instead. Structural variations between 1 and 2 are reflected in electron paramagnetic resonance spectroscopy measurements, and the permanent microporosity of 2 provides interesting functionalities to the system such as the selective adsorption of gaseous CO2 over N2.

Tailoring of a Phenothiazine Core for Electrical Conductivity and Thermal Stability: Hole-Selective Layers in Perovskite Solar Cells.

Hole-selective layers are an indispensable component for the fabrication of effective perovskite solar cells. We designed and developed two phenothiazine-based hole transport materials: PTADAnCBZ with an electron-donating sulfur atom and PTODAnCBZ with an electron-withdrawing sulfone group in the core. PTODAnCBZ in contrast to PTADAnCBZ possesses a unique molecular orbital distribution and lower dihedral angles, which endowed it with excellent optoelectrical properties, improved charge transportation, and thermal stability. The solar cells fabricated with PTODAnCBZ yielded a higher photovoltaic (PV) performance as compared to PTADAnCBZ and were on par in terms of performance with those fabricated with Spiro-OMeTAD. Notably, the phenothiazine-based PV devices showed improved stability under multi-stress conditions including moisture, moisture and light, and moisture and heat. Phenothiazine-based molecules showed unparalleled thermal stability as compared to the doped Spiro-OMeTAD. Our findings pinpoint the advantages of cost-effective phenothiazine with dioxide as hole-selective layers and suggest its application in a variety of optoelectrical devices such as PVs and organic LED.