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The simplest α,β-unsaturated sulfinyl radical CH2[double bond, length as m-dash]C(H)SO˙ has been generated in the gas phase by high-vacuum flash pyrolysis (HVFP) of sulfoxide CH2[double bond, length as m-dash]C(H)S(O)CF3 at ca. 800 °C. Two planar cis and trans conformers of CH2[double bond, length as m-dash]C(H)SO˙ were isolated in cryogenic matrixes (N2, Ne, and Ar) and characterized with IR and UV/Vis spectroscopy. In addition to the photo-induced cis ⇋ trans conformational interconversion, CH2[double bond, length as m-dash]C(H)SO˙ displays complex photochemistry. Upon irradiation with a purple light LED (400 nm), CH2[double bond, length as m-dash]C(H)SO˙ isomerizes to novel radicals CH3SCO˙, ˙CH2SC(O)H, and ˙CH2C(O)SH with concomitant dissociation to a caged molecular complex CH3S˙CO. Subsequent UV-laser (266 nm) irradiation causes fragmentation to ˙CH3/OCS and additional formation of an elusive carbonyl radical CH3C(O)S˙, which rearranges to ˙CH2C(O)SH upon further UV-light irradiation (365 nm). The vibrational data and bonding analysis of the two conformers of CH2[double bond, length as m-dash]C(H)SO˙ suggest that both are floppy radicals in which the unpaired electron conjugates with the vicinal π(C[double bond, length as m-dash]C) bond, leading to significant contribution of the canonical resonance form of ˙CH2-C(H)SO. The mechanism for the isomerization of CH2[double bond, length as m-dash]C(H)SO˙ is discussed based on the observed intermediates along with a computed potential energy profile at the CCSD(T)-F12a/aug-cc-pVTZ//B3LYP/6-311++G(3df,3pd) level of theory.

Difluorothiophosphoryl isocyanate, F2P(S)NCO was characterized with UV/vis, NMR, IR (gas and Ar‐matrix), and Raman (liquid) spectroscopy. Its molecular structure was also established by means of gas electron diffraction (GED) and single crystal X‐ray diffraction (XRD) in the gas phase and solid state, respectively. The analysis of the spectroscopic data and molecular structures is complemented by extensive quantum‐chemical calculations. Theoretically, the C s symmetric syn‐conformer is predicted to be the most stable conformation. Rotation about the P−N bond requires about 9 kJ mol−1 and the predicted existence of an anti‐conformer is dependent on the quantum‐chemical method used. This syn‐orientation of the isocyanate group is the only one found in the gas phase and contained likewise in the crystal. The overall molecular structure is very similar in gas and solid, despite in the solid state the molecules arrange through intramolecular O⋅⋅⋅F contacts into layers, which are further interconnected by S⋅⋅⋅N, S⋅⋅⋅C and C⋅⋅⋅F contacts. Additionally, the photodecomposition of F2P(S)NCO to form CO, F2P(S)N, and F2PNCO is observed in the solid Ar‐matrix., All about isocyanates: Difluorothiophosphoryl isocyanate, F2P(S)NCO, was investigated using an experimental multimethod approach in the gaseous, liquid and solid state to elucidate its structure, vibrational behaviour and photodecomposition: spectroscopy (UV/Vis, NMR, IR, Raman) and gas electron as well as single‐crystal X‐ray diffraction and in addition quantum‐chemical calculations.

Metaphosphorous acid (HOPO), a key intermediate in phosphorus chemistry, has been generated in syn- and anti-conformations in the gas phase by high-vacuum flash pyrolysis (HVFP) of a molecular precursor ethoxyphosphinidene oxide (EtOPO→C2 H4 +HOPO) at ca. 1000 K and subsequently trapped in an N2 -matrix at 2.8 K. Unlike the two conformers of the nitrogen analogue HONO, the anti-conformer of HOPO undergoes spontaneous rotamerization at 2.8 K via hydrogen-atom tunneling (HAT) with noticeable kinetic isotope effects for H/D (>104 for DOPO) and 16 O/18 O (1.19 for H18 OPO and 1.06 for HOP18 O) in N2 -matrices.

Reduced Graphene Oxide (RGO)/polyaniline (PANI) composite aerogels (GPA) with uniformly distributed PANI nanosheets were prepared by a facile self-assembly way. The fabricated hybrids present a cro...

Two new heteroarylnitrenes, 3-nitrene-2-formylthiophene (15/15') and 3-nitrene-2-formylfuran (16/16'), in the triplet ground state have been generated in solid Ar (10.0 K) and N2 (15.0 K) matrices by the 266 nm laser photolysis of 3-azido-2-formylthiophene (13) and 3-azido-2-formylfuran (14), respectively. According to the characterization with matrix-isolation IR spectroscopy and quantum chemical calculations at the B3LYP/6-311++G(3df,3pd) level, both nitrenes exhibit two conformations depending on the orientation of the formyl groups. Upon subsequent green-light irradiation (532 nm), both the nitrenes 15/15' and 16/16' undergo ring closure to form 3,2-thienoisoxazole (17) and 3,2-furoisoxazole (18), respectively. Traces of 3-imino-4,5-dihydrothiophene-2-ketene (19), formally formed through the intramolecular 1,4-H shift in the corresponding nitrenes 15/15', have been also identified among the laser photolysis products of the azide 13. In sharp contrast to the photochemistry, the high-vacuum flash pyrolysis (HVFP) of the azide 13 at ca. 1000 K mainly yields imino ketene in two conformations 19/19' together with traces of isoxazole 17. In addition to the reversible conformational interconversion in the imino ketene 19 ↔ 19', the photoisomerization from isoxazole 17 to imino ketene 19 has also been observed. The HVFP of the azide 14 at ca. 1000 K results in complete dissociation to HCN, C2H2, CO, CO2, H2O, and N2. Unlike the recently disclosed hydrogen-atom tunneling (HAT) in the transformation from the structurally related 2-formyl phenylnitrene (2) to imino ketene 3 in a cryogenic Ar-matrix, the absence of HAT in nitrenes 15 and 16 can be reasonably explained by the higher barrier heights and also larger barrier widths in the isomerization reactions.

Small molecules solely consisting of H, N, O, and S are highly relevant intermediates in atmospheric chemistry and biology. Even though several isomers of [HNO2S] have been computationally predicted, only the IR spectra for the two lowest-energy isomers HNSO2 and syn–syn HONSO have been previously reported. Herein, the photochemistry (193 nm laser) of HNSO2 in N2-, Ne-, and Ar-matrices (≤15 K) has been studied. Aside from syn–syn HONSO, several new isomers including anti–syn HONSO, gauche–syn HOSNO, syn HOS(O)N, anti HOS(O)N, syn HS(O)NO, anti HN(O)SO, gauche–syn HSONO, and an elusive caged-radical pair HOS˙⋯˙NO have been identified. Additionally, the formation of fragments HONO, HO˙, ˙NO, and ˙NO2 has also been observed. The characterization of these species with matrix-isolation IR and UV/Vis spectroscopy is supported by 15N-labeling and quantum chemical computations at the B3LYP/6-311++G(3df,3pd) level. Furthermore, the photo-induced isomerization reactions, including the conformational conversion of syn–syn HONSO → anti–syn HONSO and reversible isomerization of HOSNO ↔ anti–syn HONSO, syn–syn HONSO ↔ HN(O)SO, HSONO ↔ HS(O)NO, and HOS˙⋯˙NO ↔ HOSNO have also been observed, and the underlying mechanism is discussed.

By high-vacuum flash pyrolysis of bis(trifluoromethyl)disulfane oxide (CF3S(O)SCF3) at 400 °C, the elusive trifluoromethylthiyl radical (CF3S˙) has been efficiently generated in the gas phase. Subsequent isolation of CF3S˙ in cryogenic matrixes (Ne, Ar, and N2) allows a first time characterization with IR and UV-vis spectroscopy by combining with computations at the CCSD(T)/aug-cc-pV(T + d)Z level. In addition to the photo-induced sulfur atom transfer (SAT) from CF3S˙ to N2 and CO and the isomerization to ˙CF2SF, the O2-oxidation via the intermediacy of the novel thiylperoxy radical CF3SOO˙ has been observed.

The absorption of conventional metamaterial absorbers (MMAs), originating from the electric or magnetic resonance induced ohmic loss, usually has a narrow bandwidth because of the limited surface resistance of the structured metal layers. In this letter, we experimentally demonstrate a broadband MMA by using graphite instead of copper to construct the surface pattern structure. Compared with metals, the graphite has a low electric conductivity, and its skin depth is far more than those of metals. As a result, the effective thickness of our graphite-based absorber, which determines the thickness-dependent resonance, is very sensitive to the thickness of the structured graphite layer. Due to the relatively large surface resistance and the sensitive tunable thickness-dependent resonance, our design achieves an absorption bandwidth (less than –10 dB) from 12.7 to 18 GHz. Our results may provide an effective way to tune the thickness-dependent resonance and to broaden the absorption bandwidth of MMA.

Impedance matching is primary for broadband and strong absorption. Here, we optimized the impedance matching condition of the carbonyl iron powders (CIPs) layer by stacking the layered ultra high molecular weight polyethylene (UHMWPE). The double-layer absorber with its absorption more than 90% within the frequency range of 4.4–18 GHz is obtained by simulation and validated by experiment, while the single CIPs layer shows its broadest bandwidth only within 4.8–8.4 GHz. By simulating the angular performance, the double-layer has been confirmed to be omnidirectional and polarization insensitive. Besides, the impedance matching property of the double-layer is highly correlated with the thickness of UHMWPE layer, and the broadband absorption is resulted from the combination of the impedance matching layer and the absorbing layer. The designed absorber, stacked with the impact resistant UHMWPE layer, has great prospects for practical application under the requirement for bulletproof property.

S-Nitrosothiols (RSNO) are exogenous and endogenous sources of nitric oxide in biological systems due to facile homolytic cleavage of the S-N bonds. By following the photolytic decomposition of prototypical RSNO (R = Me and Et) in Ne, Ar, and N2 matrixes (

The elusive heterocumulenic radical OCCNO˙ and its isotopologues OC13CNO˙ and OCC15NO˙ have been prepared by reacting photolytically generated unsaturated carbene OCC/OC13C with ˙NO/15˙NO in cryogenic N2-, Ar-, and Ne-matrices. Upon UV-light (365 nm) irradiation, the C-C bond in OCCNO˙ breaks and yields a long-sought ground-state radical CNO˙ (X2Π), which has also been identified with matrix-isolation infrared spectroscopy.

Background Cytotoxic cancer treatments, such as irradiation, can cause permanent sterility in male mammals owing to the loss of spermatogonial stem cells. In animal models, spermatogenesis could be restored from transplanted spermatogonial stem cells. Previously, we showed that transient suppression of FSH, LH, and testosterone in the recipient with a gonadotropin-releasing hormone antagonist (GnRH-ant), given immediately after irradiation, enhanced spermatogenesis from transplanted spermatogonial stem cells in mice and monkeys. Objectives To explore improvements in the preparation of the recipient for efficient and reliable spermatogenic recovery from spermatogonial stem cell transplantation, so that it can be used effectively in clinical practice. Materials and methods In mouse recipients, we evaluated the effects of hormone suppression given after germ cell depletion was complete, which is a more clinically relevant model, and also the importance of total androgen ablation and maintenance of FSH levels. Three regimens, GnRH-ant, GnRH-ant plus flutamide (androgen receptor antagonist), and GnRH-ant plus FSH, were administered prior to and around the time of transplantation of testis cells from immature mice or from prepubertal monkeys. Results Treatment with GnRH-ant resulted in a fourfold increase in spermatogenic recovery from GFP-marked transplanted mouse cells. Total androgen ablation with the addition of flutamide, started two weeks before transplantation, did not further enhance recovery. Surprisingly, FSH supplementation, started around the time of transplantation, actually reduced spermatogenic recovery from transplanted spermatogonial stem cells in GnRH-ant-treated mice. When prepubertal monkey testicular cells were transplanted into nude mice that were given the same hormone treatments, the numbers of donor-derived colonies were independent of hormone treatment. Discussion and conclusion The enhancements in spermatogenic recovery may only occur when syngeneic or closely related donor-recipient pairs are used. These results are useful in further investigations in choosing a hormone suppression regimen in combination with spermatogonial transplantation as a treatment to restore fertility in primates after cytotoxic therapy.

Two carbonyl pseudohalogen compounds CF2HC(O)NCO and CF2HC(O)NCS have been synthesized and fully characterized by IR (gas-phase, matrix-isolation), Raman (liquid), UV–vis (gas-phase), and NMR (19F, 13C, 1H) spectroscopy. The conformational properties and photochemistry of both species have been studied by combining matrix-isolation IR spectroscopy and quantum chemical calculations with the B3LYP, MPW1PW91, CBS-QB3 methods. Two conformers (syn and anti), depending on the configuration between the C O and pseudohalogen ligands (NCO and NCS), have been unambiguously identified in both gas phase and solid noble gas matrices (Ar and Ne). Consistent with the theoretical calculations, the syn conformation is energetically more favorable. Upon irradiation with an ArF excimer laser (193 nm), CF2HC(O)NCO and CF2HC(O)NCS in cryogenic matrices eliminate CO and yield CF2HNCO and CF2HNCS, respectively. The underlying mechanism for the photochemistry of CF2HC(O)NCO is rationalized by the elimination of the carbonyl rather than the isocyanato C O moiety.

A rare oxyphosphinidene (Me—OP) has been generated in the triplet ground state through either photolysis (266 nm) or flash-vacuum pyrolysis (FVP, 700 °C) of methoxydiazidophosphine MeOP(N3)2. Upon ArF laser irradiation (193 nm), an unprecedented isomerization from Me—OP to the long-sought methylphosphinidene oxide (Me—PO) occurs in cryogenic Ne- and N2-matrices. Alternatively, the latter can be efficiently generated through photolysis (193 nm) or FVP (ca. 700 °C) of methylphosphoryl diazide MeP(O)(N3)2, in which the elusive nitrene intermediate MeP(O)(N3)N in the triplet ground state has been also observed by IR (with 15N-labeling) and EPR (|D/hc| = 1.545 cm–1 and |E/hc| = 0.003 95 cm–1) spectroscopy.

The simplest alkynyl thiocyanate HCCSCN has been synthesized and characterized for the first time. HCCSCN is surprisingly stable at room temperature but undergoes photoisomerization in an Ar-matrix (10 K) to yield the novel sulfenyl isocyanide HCCSNC and thioketene NCC(H)CS. The isomeric isothiocyanate HCCNCS, missing in the photochemistry of HCCSCN, can be generated through the photodecarbonylation of propiolyl isothiocyanate.

Arylsulfinyl radicals are key intermediates in sulfoxide chemistry. The parent molecule, phenylsulfinyl radical PhSO•, has been generated for the first time in the gas phase through high-vacuum flash pyrolysis of PhS(O)R (R = CF3 and Cl) at about 1000 K. Upon UV light irradiation (365 nm), PhSO• isomerizes to novel oxathiyl radical PhOS• in cryogenic matrices (2.8 K). Prolonged irradiation causes further isomerization of PhOS• to 2-hydroxyphenylthiyl radical, the formation of which has been also observed in the 193 nm laser photolysis of matrix-isolated 2-hydroxybenzenethiol. Concomitantly, ring-opening occurs during the UV photolysis of PhOS• and 2-hydroxybenzenethiol and forms an acyclic thioketoketene radical. Phenylsulfinyl radical reacts partially with molecular oxygen in the gas phase and yields phenyl radical Ph• and OSOO. Upon irradiation (365 nm), the isomeric oxathiyl radical also combines O2 with immediate dissociation to phenoxy radical PhO• and SO2. The identification of the intermediates wit...

The simplest aminosulfinyl radical H2 NSO has been generated in the gas phase through flash vacuum pyrolysis of CF3 S(O)NH2 at approximately 1000 K. Upon UV light irradiation (365 nm), 1,3-H migration occurs in H2 NSO and furnishes an elusive N-amidyl radical HNSOH in syn and anti conformations in cryogenic matrices (N2 or Ar, 15 K). Further 266 nm laser irradiation results in dissociation of HNSOH to H2 O and SN and concomitant reformation of H2 NSO in trace amount. The identification of H2 NSO, syn-HNSOH, and anti-HNSOH by matrix-isolation IR spectroscopy is supported by high-level quantum chemical computations.

Disulfur dioxide, OSSO, has been proposed as the enigmatic "near-UV absorber" in the yellowish atmosphere of Venus. However, the fundamentally important spectroscopic properties and photochemistry of OSSO are scarcely documented. By either condensing gaseous SO or 266 laser photolysis of an S2O2 complex in Ar or N2 at 15 K, syn-OSSO, anti-OSSO, and cyclic OS([double bond, length as m-dash]O)S were identified by IR and UV/Vis spectroscopy for the first time. The observed absorptions (λmax) for OSSO at 517 and 390 nm coincide with the near-UV absorption (320-400 nm) found in the Venus clouds by photometric measurements with the Pioneer Venus orbiter. Subsequent UV light irradiation (365 nm) depletes syn-OSSO and anti-OSSO and yields a fourth isomer, syn-OSOS, with concomitant dissociation into SO2 and elemental sulfur.

When mixing SO with O2 in N2, Ne, or Ar, an end-on complex OS–OO forms in the gas phase and can subsequently be trapped at cryogenic temperatures (2.8–15.0 K). Upon infrared light irradiation, OS–OO converts to SO3 and SO2 + O with the concomitant formation of a rare 1,2,3-dioxathiirane 2-oxide, i.e., cyclic OS(O)O. Unexpectedly, the ring-closure of 16OS–18O18O yields a ca. 2 : 1 mixture of cyclic 18OS(16O)18O and 16OS(18O)18O. The characterization of OS–OO and OS(O)O with IR and UV/Vis spectroscopy is supported by high-level ab initio computations.

Chemical reactions involving quantum mechanical tunneling (QMT) increasingly attract the attention of natural scientists. In contrast to the hydrogen-tunneling as frequently observed in chemistry and biology, tunneling solely by heavy atoms is rare. Herein, we report the clear-cut heavy-atom tunneling in trifluoroacetyl nitrene, CF3C(O)N. Specifically, the carbonyl nitrene CF3C(O)N in the triplet ground state was generated in cryogenic matrices by laser (193 or 266 nm) photolysis of CF3C(O)N3 and characterized by IR and EPR spectroscopy. In contrast to the theoretically predicted activation barriers (> 10 kcal mol-1), CF3C(O)N undergoes rapid rearrangement into CF3NCO with half-life times of less than 10 minutes and unprecedentedly large 14N/15N kinetic isotope effects (1.18-1.33) in solid Ar, Ne, and N2 matrices even at 2.8 K. The tunneling disappearance of CF3C(O)N becomes much slower in the chemically active toluene and in 2-methyltetrahydrofuran at 5 K.

The parent thioketene S-oxide H2 CCSO has been generated in the gas phase through flash vacuum pyrolysis (ca. 1000 K) of vinyl sulfoxide H2 CC(Br)-S(O)CF3 via the intermediacy of a novel vinyl sulfinyl radical H2 C=C(Br)-SO (syn and anti conformers). Upon irradiation at 266 nm, H2 CCSO decomposes into HCCH/SO and H2 CS/CO in cryogenic Ar matrix. Whereas, visible-light irradiations result in syn↔anti conformational interconversion in H2 C=C(Br)-SO. The molecular structures of H2 CCSO and isomers are computationally studied at the CCSD(T)-F12/VTZ-F12 level of theory, and the bonding properties of H2 CCSO are analyzed with the EDA-NOCV method at the M06-2X/TZ2P level.

Methylsulfoxide radicals CH3SOx (x = 1–4) are key reactive sulfur species (RSS) in the atmospheric oxidation of volatile organic sulfur compounds (VOSCs). Through flash vacuum pyrolysis (FVP) of trifluoromethanesulfinic acid methyl ester CF3S(O)OCH3 at 1000 K, the methoxysulfinyl radical CH3OSO has been generated in the gas phase and subsequently characterized in cryogenic N2, Ar, and Ne matrices by IR spectroscopy. Upon 266 nm laser irradiation, CH3OSO efficiently isomerizes to the less stable methylsulfonyl radical CH3SO2 in matrices without noticeable decomposition. In the gas phase, CH3OSO reacts with O2 and yields sulfinyl peroxyl radical CH3OS(O)OO, a new member in the CH3SOx (x = 1–4) family. This radical dissociates into SO3 and CH3O with the intermediacy of the sulfonyoxyl radical CH3OSO3 under the 266 nm laser irradiation. Additionally, the photoisomerization of CF3S(O)OCH3 to sulfenic ester CF3OSOCH3 was also observed.

Difluoroacetyl azide, CHF 2 C(O)N 3 , has been synthesized and characterized. The azide decomposes slowly at room temperature (300 K) into N 2 and difluoromethyl isocyanate CHF 2 NCO, which has also been isolated as neat substance and fully characterized. The elusive nitrene intermediate CHF 2 C(O)N in the stepwise Curtius-rearrangement of the azide is tentatively identified by IR spectroscopy during the 193 nm laser photolysis of the azide in solid Ne matrix at 2.8 K. Unexpectedly, flash vacuum pyrolysis (FVP) of CHF 2 C(O)N 3 at 500 K yields a novel carbonyl isocyanide FC(O)NC with N 2 , HF, FCN, CO, and traces of CHF 2 NCO. Subsequent irradiation (193 nm) of the pyrolysis products results in the rearrangement of FC(O)NC to FC(O)CN. According to the quantum chemical calculations (B3LYP and CCSD(T)), the azide CHF 2 C(O)N 3 prefers concerted Curtius rearrangement with minor contribution of the stepwise decomposition. The thermally generated CHF 2 NCO eliminates HF and forms FC(O)NC solely under the pyrolysis conditions, whereas, no HF-elimination occurs to isolated CHF 2 NCO even at 1000 K due to a formidable activation barrier.

Methoxysulfinyl azide, CH3OS(O)N3, which is unstable at room temperature, has been synthesized and characterized as neat substance for the first time. Its decomposition in the gas phase has been studied by combining flash vacuum pyrolysis (FVP) and matrix isolation IR spectroscopy. The novel dipolar nitrene intermediate, CH3OS(O)N, in the singlet ground state with two distinct conformations (syn and anti) has been identified among the FVP products at 600 K. At higher FVP temperature (800 K) the nitrene undergoes further fragmentation into HNSO and H2CO. The stepwise decomposition mechanism of CH3OS(O)N3 is supported by the quantum chemical calculations.

Neutral five-atomic cumulenes formally consisting of two pseudohalogens (e.g., NCO, NNN, NSO) by sharing the central nitrogen atom are exotic species that have been barely studied. Through flash vacuum pyrolysis of CF3S(O)NCO at ca. 1200 K, sulfinyl isocyanate, bearing resonance structures of O=C−N=S=O and O=C=N−S=O, has been generated in the gas phase and subsequently characterized in cryogenic matrices (Ar and N2). Its reversible conformational (syn and anti) interconversion and photodecomposition were observed.

N-Methylcarbamoyl azide Me(H)NC(O)N3 has been synthesized and structurally characterized. Both N3 and CH3 groups in the molecule adopt a syn conformation with the CO bond. Upon flash vacuum pyrolysis at 800 K, the azide mainly decomposes into Me(H)NNCO/N2 and MeNCO/HN3 through Curtius-rearrangement and a retro-ene reaction, respectively. In contrast, 193 and 266 nm laser photolysis of Me(H)NC(O)N3 in cryogenic matrices (Ar, Ne, and N2) leads to stepwise Curtius-rearrangement via the intermediacy of carbamoylnitrene Me(H)NC(O)N, for which two conformers with the CH3 group being in syn and anti conformations to the CO bond have been unambiguously identified by matrix-isolation IR spectroscopy. Triplet multiplicity of Me(H)NC(O)N (|D/hc| = 1.57 cm−1 and |E/hc| = 0.012 cm−1) and another two carbamoylnitrenes H2NC(O)N (|D/hc| = 1.59 cm−1 and |E/hc| = 0.018 cm−1) and Me2NC(O)N (|D/hc| = 1.55 cm−1 and |E/hc| = 0.016 cm−1) has been further established by matrix-isolation EPR spectroscopy. Subsequent visible light irradiation (420–460 nm) of Me(H)NC(O)N results in the exclusive formation of Me(H)NNCO. The molecular structures of Me(H)NC(O)N3 and Me(H)NC(O)N, multiplicities of the nitrene, and the underlying mechanism for the decomposition of the azide are reasonably explained with quantum chemical calculations by utilizing the B3LYP, CBS-QB3, CCSD(T), and CASPT2 methods.

A biologically relevant reactive sulfur species (RSS), the hypothiocyanite radical OSCN, is generated in the gas phase through flash vacuum pyrolysis (FVP) of trifluoromethyl sulfinyl cyanide CF3S(O)CN at ca. 1000 K. Upon UV light irradiation (365 nm), OSCN rearranges to novel isomers OSNC and SOCN, and further visible light irradiation (400 ± 20 nm) leads to reverse isomerization. The identification of OSCN, OSNC, and SOCN in cryogenic matrices (Ar and N2, 2.8 K) with IR spectroscopy is supported by quantum chemical calculations up to the CCSD(T)-F12/VTZ-F12 level. The potential energy surface for the interconversion of OSCN isomers and their bonding properties are computationally explored by using the CCSD(T)-F12/VTZ-F12 and EDA-NOCV methods, respectively.

The simplest alkoxycarbonylnitrene, CH3OC(O)N, has been generated through laser (266 and 193 nm) photolysis of CH3OC(O)N3 and CH3OC(O)NCO and subsequently characterized by IR (15N, D-labelling) and EPR (|D/hc| = 1.66 cm−1 and |E/hc| = 0.020 cm−1) spectroscopy in cryogenic matrices. Two conformers of the nitrene, with the CH3 group being in syn or anti configuration to the CO bond, have been unambiguously identified. Further UV light irradiation (365 nm) of the nitrene results in isomerization to CH3ONCO, completing the frequently explored mechanism for the Curtius-rearrangement of CH3OC(O)N3.

The stepwise decomposition of carbonyl diisocyanate, OC(NCO)2, has been studied by IR spectroscopy in solid argon matrices at 16 K. Upon an ArF laser (193 nm) irradiation, carbonyl diisocyanate splits off CO and furnishes a novel carbonyl nitrene, OCNC(O)N, in its triplet ground state. Two conformers of the nitrene, syn and anti, derived from the two conformers of OC(NCO)2 (62% syn-syn and 38% syn-anti) are identified and characterized by combining IR spectroscopy and quantum chemical calculations. Subsequent visible light (> 395 nm) irradiation causes the Curtius-rearrangement of the nitrene towards OCNNCO. In addition to the expected decomposition products N2 and CO, further ArF laser photolysis of OCNNCO can yield NOCN through diazomethanone (NNCO) intermediate. To further validate the reaction mechanism, the ArF laser photolysis of the closely related NNNNCO and cyclo-N2CO in solid argon matrices has been studied. The observation of NOCN and in situ CO-trapping product OCNNCO provides indirect evidence to support the initial generation of NNCO as the common intermediate during the laser photolysis of OCNNCO, NNNNCO, and cyclo-N2CO.

The parent sulfonyl azide CH3SO2N3 has been characterized in a neat form by IR (gas, matrix-isolation) and Raman (solid) spectroscopy, and its structure has been established by X-ray crystallography. In both gas phase and solid state, the azide exhibits single conformation with the azido ligand being synperiplanar to one of the two S═O groups. In the crystal molecules of CH3SO2N3 are interconnected through three-dimensional O···H-C-H···O hydrogen bonds. Upon an ArF laser (193 nm) photolysis, the azide in solid noble gas matrices splits off N2 and yields the sulfonyl nitrene CH3SO2N in the triplet ground state. Subsequent photolysis with UV light (266 nm) causes the transformation from the nitrene to the pseudo-Curtius rearrangement product CH3NSO2. The identification of the photolysis intermediates by matrix-isolation IR spectroscopy is supported by quantum chemical calculations with DFT methods.

The dipolar oxathiazyne-like sulfinylnitrene RS(O)N, a highly reactive α-oxo nitrene, has been rarely investigated. Upon flash vacuum pyrolysis of sulfinyl azide CF3S(O)N3 at 350 °C, an elusive sulfinylnitrene CF3S(O)N was generated in the gas phase in its singlet ground state and was characterized by matrix-isolation IR spectroscopy. Further fragmentation of CF3S(O)N at 600 °C produced CF3 and a novel iminyl radical OSN, an SO2 analogue, which were unambiguously identified by IR spectroscopy. Consistent with the experimental observations, DFT calculations clearly support a stepwise decomposition mechanism of CF3S(O)N3.

Synthesis of azido(trimethylsilyl)acetylene (6) was performed by treating the iodonium salt 5 with highly soluble hexadecyltributylphosphonium azide (QN₃) at -40 °C. Although this product is very unstable, it can nevertheless be trapped by the click reaction with cyclooctyne to give the corresponding 1,2,3-triazole, and also directly characterized by ¹H- and (13)C-NMR data as well as IR-spectra, which were measured in solution at low temperature and in the gas phase. The thermal or photochemical decay of azide 6 leads to cyano(trimethylsilyl)carbene. This is demonstrated not only by quantum chemical calculations, but also by the trapping reactions with the help of isobutene.

Elusive [S, S, N, O] isomers including the perthiyl radical •SSNO are S/N hybrid species in the complex bioinorganic chemistry of signaling molecules H2S and •NO. By mixing thermally generated disulfur (S2) with •NO in the gas phase, •SSNO was generated and subsequently isolated in cryogenic Ar- and N2-matrices at 10.0 K and 15.0 K, respectively. Upon irradiation with a 266 nm laser, •SSNO isomerizes to novel sulfinyl radicals cis-NSSO• and trans-NSSO• as well as thiyl radicals cis-OSNS• and trans-OSNS•, which have been characterized by combining matrix-isolation IR (15N-labeling) and UV/Vis spectroscopy and quantum chemical calculations at the CCSD(T)-F12/cc-pVTZ-F12 level of theory. The photo-induced reversible interconversion between NSSO• and OSNS• has also been observed.

In this paper, we measured and compared the permittivity of graphene oxide aqueous solution (GOAS) and water, which confirmed the better absorption performance of GOAS. Based on the better absorbent, we experimentally demonstrated a GOAS-based metamaterial absorber by directly injecting GOAS into 3D-printed container, and validated its absorption bandwidth within 5.2–18 GHz.The high absorption efficiency is mainly resulted from the coupling effects between neighboring GOAS circles and power loss confinement induced by magnetic loop, while the frequency-dispersed permittivity of GOAS guaranteed its broadband absorption property. Our results illustrate the practicability to achieve better absorption of aqueous solution, and broaden its bandwidth by constructing absorbing structure.

This paper proposes a 3D-printed pyramidal absorber, which comprises of the printing filaments, carbon-loaded Acrylonitrile Butadiene Styrene (ABS). This ABS has certain absorption effects, and shows simple and rapid prototyping characteristics. Here, we experimentally demonstrated the directly printed pyramidal absorber showing the absorption more than 90% within the frequency range from 5.3 to 18 GHz. The incident energy at the low and high peak frequencies are mostly attenuated by λ/4 resonances, corresponding to the wavelength of λ/4 and 3λ/4 separately. Distinct from the flat absorber, the pyramidal structure and absorbent take synergistic effects for broadband absorption. Additionally, the pyramid maintained its absorption bandwidth within quite a wide incident angle, 50° for transverse electric (TE) polarization and 60° for transverse magnetic (TM) polarization. It is expected that the proposed pyramidal absorber has great potential for application in radar cross section reduction and electromagnetic shielding.

Designing heating process to obtain beaded chains nanostructures was an effective way to improve electromagnetic wave absorbing properties of SiC. In this work, the beaded chains SiC nanocomposites deposited carbon coating contained homogeneously-distributed ZrC nanoparticles. The dielectric loss of the beaded chains ZrC/C/SiC nanocomposites were investigated in a frequency of 2.0–18.0 GHz, which was increased by about 10 times than the nanowires, reaching 0.41, and the maximum value is 0.66. It was observed that the heterogeneous interface between C, ZrC and SiC, carbon defects and beaded chains nanostructures could effectively enhance the microwave absorption properties of the nanocomposites.

Cyclic PON, a first 16-electron triatomic ring consisting of two first-row elements, has been generated through 193 nm laser photolysis of OPN in cryogenic matrices. When the photolysis (365 nm) was performed in the presence of CO, OPN combines CO and furnishes an exotic acyclic molecule OPNCO. Upon the 193 nm laser irradiation, OPNCO dissociates mainly to OPN and CO with traces of PN and CO2 . The identification of cyclic PON and OPNCO with IR spectroscopy is supported by 15 N-labeling experiments and quantum chemical calculations.

The aim of this study was to explore whether nutrition supply can improve the drought tolerance of Moso bamboo under dry conditions. One-year-old seedlings were exposed to two soil water content levels [wellwatered, 70 ± 5% soil-relative-water-content (SRWC) and drought stress, 30 ± 5% SRWC] and four combinations of nitrogen (N) and phosphorus (P) supply (low-N, low-P, LNLP; low-N, high-P, LNHP; high-N, high-P, HNHP; and high-N, low-P, HNLP) for four months. Plant growth, photosynthesis, chlorophyll fluorescence, water use efficiency and cell membrane stability were determined. The results showed that drought stress significantly decreased total biomass, net-photosynthesis (Pn), stomatal-conductance (gs), leaf-chlorophyll-content (Chlleaf), PSII-quantum-yield (ΦPSII), maximum-quantum-yield-of-photosynthesis (Fv/Fm), photochemical-quenching-coefficient (qP), leaf-instantaneous-water-use efficiency (WUEi), relative-water-content (RWC), photosynthetic-N-use-efficiency (PNUE), and photosynthetic-P-use-efficiency (PPUE). N and P application was found to be effective in enhancing the concentration of leaf N, gs, and Pn while reducing the production of reactive oxygen species under both water regimes. Under LNHP, HNHP and HNLP treatments, the decreases in total biomass, Pn, Chlleaf and Fv/Fm of drought-stressed were less evident than the decreases under LNLP. The study suggests that nutrient application has the potential to mitigate the drastic effects of water stress on Moso bamboo by improving photosynthetic rate, water-use efficiency, and increasing of membrane integrity.

An exotic ternary S, N, O heterocumulene OSNSO in syn-syn (A) and syn-anti (B) conformations has been generated in the gas phase through flash vacuum pyrolysis of CF3S(O)NSO at 700 K. Upon visible light irradiation (570 ± 20 or 532 nm), both A and B, isolated in cryogenic matrices (N2, Ne, Ar, and Kr

Two simple acylnitrenes, 2-furoylnitrene (2) and 3-furoylnitrene (6), were generated through 266 nm laser photolysis of the corresponding azides. Both are magnetically bistable in cryogenic matrices, as evidenced by the direct observation of the closed-shell singlet state with IR spectroscopy in solid Ne, Ar, Kr, Xe, and N2 matrices (3–40 K) and the triplet state in toluene (10 K) with EPR spectroscopy (32: |D/hc| = 1.48 cm–1 and |E/hc| = 0.029 cm–1; 36: |D/hc| = 1.39 cm–1 and |E/hc|c = 0.039 cm–1). Subsequent visible-light and UV laser irradiations led to the formation of furyl isocyanates (3 and 7) and ring-opening product 3-cyanoacrolein (9-E and 9-Z), respectively, in which the elusive 3-furylnitrene (38) was also identified by IR and EPR spectroscopy (|D/hc| = 1.12 cm–1 and |E/hc| = 0.005 cm–1).

Two hitherto unreported sulfur-centered radicals CF3 SO. and CF3 OS. were generated in the gas phase through high-vacuum flash pyrolyses of sulfoxide CF3 S(O)X (X=CF3 , Cl, PhO) precursors. The CF3 OS. molecule is the first experimental example that constitutes an oxathiyl radical. It was isolated and characterized by combining matrix-isolation IR and UV/Vis spectroscopy with quantum chemical computations up to the UCCSD(T)-F12/cc-pVTZ-F12 level of theory. Upon UV light irradiation (254 or 266 nm), sulfinyl radical (CF3 SO. ) isomerizes to oxathiyl radical (CF3 OS. ) in cryogenic noble gas matrices (Ar and Ne). Natural population analyses at the BP86/def2-TZVPP//UCCSD(T)-F12/cc-pVTZ-F12 level suggest that the spin density in CF3 OS. is mainly localized on the sulfur atom (0.86), whereas, in CF3 SO. the spin density is almost equally distributed on the sulfur (0.55) and oxygen (0.43) atoms.

Thiophosphoryl nitrenes, R2P(S)N, are thiazirine-like intermediates that have been chemically inferred from trapping products in early solution studies. In this work, photolysis of the simplest thiophosphoryl azide, F2P(S)N3, in solid noble-gas matrices enabled a first-time spectroscopic (IR and UV-vis) identification of the thiophosphoryl nitrene F2P(S)N in its singlet ground state. Upon visible-light irradiation (≥495 nm), it converts into the thionitroso isomer F2P-N═S, which can also be produced in the gas phase from flash vacuum pyrolysis of F2P(S)N3. Further irradiation of F2P-NS with 365 nm UV light leads to the reformation of F2P(S)N and isomerization to the thiazyl species F2P-S≡N.

The simplest N-sulfonylamine HNSO2 has been generated in the gas phase through flash vacuum pyrolysis of methoxysulfonyl azide CH3OS(O)2N3. Its identification was accomplished by combining matrix-isolation IR spectroscopy and quantum chemical calculations. Both experimental and theoretical evidence suggest a stepwise decomposition of the azide via the methoxysulfonyl nitrene CH3OS(O)2N, observed in the 193 nm laser photolysis of the azide, with concerted fragmentation into CH2O and HNSO2. Upon the 193 nm laser irradiation, HNSO2 isomerizes into the novel N-hydroxysulfinylamine HONSO.

The Ni@C composites were successfully synthesized by thermal decomposition of a Ni-based metal organic framework (Ni-MOF). By varying the pyrolysis temperature, Ni@C composites with different morphology and microstructure can be easily synthesized. Benefiting from the synergistic effect between the Ni core and carbon shell, the composite possess good impedance matching and excellent microwave absorption performance. Interestingly, the strongest absorption of the Ni@C composite reaches −55.7 dB corresponding to 6.0 GHz absorption bandwidth (

In oil and gas exploration of Block K in Amu Darya basin Uzbekistan, the reservoir lithologies are mainly in different carbonate rocks, the more types of rocks, the more various reservoir space is, as a result, it brings some difficulties to the reservoir quantitative evaluation. Therefore, according to this situation that the difficulty in identification of complex carbonate lithologies is, in this study block, artificial neural network analysis method is used in this paper. The method combines mud logging, cutting, core data, well logging, studies logging response characteristics of the different types of carbonate rocks, establishes lithology identification index. In this study, the method is used in identifying the types of carbonate rocks, the identified result compared to actual rocks displays about 70.51~87.23%, and it plays the positive role for reservoir quantitative evaluation.