More Like this

1. On the formation of complex organic molecules in the interstellar medium: untangling the chemical complexity of carbon monoxide–hydrocarbon containing ice analogues exposed to ionizing radiation via a combined infrared and reflectron time-of-flight analysis

   https://doi.org/10.1039/C9CP01793C  

   Abplanalp, Matthew J.; Kaiser, Ralf I. (August 2019, Physical Chemistry Chemical Physics)

   Recently, over 200 molecules have been detected in the interstellar medium (ISM), with about one third being complex organic molecules (COMs), molecules containing six or more atoms. Over the last few decades, astrophysical laboratory experiments have shown that several COMs are formed via interaction of ionizing radiation within ices deposited on interstellar dust particles at 10 K (H 2 O, CH 3 OH, CO, CO 2 , CH 4 , NH 3 ). However, there is still a lack of understanding of the chemical complexity that is available through individual ice constituents. The present research investigates experimentally the synthesis of carbon, hydrogen, and oxygen bearing COMs from interstellar ice analogues containing carbon monoxide (CO) and methane (CH 4 ), ethane (C 2 H 6 ), ethylene (C 2 H 4 ), or acetylene (C 2 H 2 ) exposed to ionizing radiation. Utilizing online and in situ techniques, such as infrared spectroscopy and tunable photoionization reflectron time-of-flight mass spectrometry (PI-ReTOF-MS), specific isomers produced could be characterized. A total of 12 chemically different groups were detected corresponding to C 2 H n O ( n = 2, 4, 6), C 3 H n O ( n = 2, 4, 6, 8), C 4 H n O ( n = 4, 6, 8, 10), C 5 H n O ( n = 4, 6, 8, 10), C 6 H n O ( n = 4, 6, 8, 10, 12, 14), C 2 H n O 2 ( n = 2, 4), C 3 H n O 2 ( n = 4, 6, 8), C 4 H n O 2 ( n = 4, 6, 8, 10), C 5 H n O 2 ( n = 6, 8), C 6 H n O 2 ( n = 8, 10, 12), C 4 H n O 3 ( n = 4, 6, 8), and C 5 H n O 3 ( n = 6, 8). More than half of these isomer specifically identified molecules have been identified in the ISM, and the remaining COMs detected here can be utilized to guide future astronomical observations. Of these isomers, three groups – alcohols, aldehydes, and molecules containing two of these functional groups – displayed varying degrees of unsaturation. Also, the detection of 1-propanol, 2-propanol, 1-butanal, and 2-methyl-propanal has significant implications as the propyl and isopropyl moieties (C 3 H 7 ), which have already been detected in the ISM via propyl cyanide and isopropyl cyanide, could be detected in our laboratory studies. General reaction mechanisms for their formation are also proposed, with distinct follow-up studies being imperative to elucidate the complexity of COMs synthesized in these ices. 

   more » « less
2. New germanate and mixed cobalt germanate salt inclusion materials: [(Rb ₆ F)(Rb ₄ F)][Ge ₁₄ O ₃₂ ] and [(Rb ₆ F)(Rb _3.1 Co _0.9 F _0.96 )][Co _3.8 Ge _10.2 O ₃₀ F ₂ ]

   https://doi.org/10.1039/D0CE01099E  

   Carone, Darren; Usman, Mohammad; Klepov, Vladislav V.; Smith, Mark D.; Kocevski, Vancho; Besmann, Theodore M.; zur Loye, Hans-Conrad (December 2020, CrystEngComm)

   null (Ed.)

   Single crystals of two new germanates, [(Rb 6 F)(Rb 4 F)][Ge 14 O 32 ] and [(Rb 6 F)(Rb 3.1 Co 0.9 F 0.96 )][Co 3.8 Ge 10.2 O 30 F 2 ], were synthesized via high temperature RbCl/RbF flux growth. Both compounds crystallize in the cubic space group F 4̄3 m and possess the germanium framework of the previously reported salt inclusion material (SIM), [(Cs 6 F)(Cs 3 AgF)][Ge 14 O 32 ], related to the Ge 7 O 16 zeolitic family. These materials demonstrate the ability to accommodate a variety of salt-inclusions, and exhibit chemical flexibility enabling modifications of the framework through incorporation of Co. Alteration of the salt-inclusion led to intrinsic luminescence of [(Rb 6 F)(Rb 4 F)][Ge 14 O 32 ] while modification of the framework resulted in an unanticipated Rb/Co salt/inclusion in [(Rb 6 F)(Rb 3.1 Co 0.9 F 0.96 )][Co 3.8 Ge 10.2 O 30 F 2 ]. Fluorescence measurements were performed on [(Rb 6 F)(Rb 4 F)][Ge 14 O 32 ]. First-principles calculations in the form of density functional theory (DFT) were performed for [(Rb 6 F)(Rb 3.1 Co 0.9 F 0.96 )][Co 3.8 Ge 10.2 O 30 F 2 ] to elucidate its electronic and magnetic properties, and stability at 0 K. 

   more » « less
3. The reaction of thiourea and 1,3-dimethylthiourea towards organoiodines: oxidative bond formation and halogen bonding

   https://doi.org/10.1107/S205322962100869X  

   Peloquin, Andrew J.; Ragusa, Arianna C.; McMillen, Colin D.; Pennington, William T. (October 2021, Acta Crystallographica Section C Structural Chemistry)

   By varying the halogen-bond-donor molecule, 11 new halogen-bonding cocrystals involving thiourea or 1,3-dimethylthiourea were obtained, namely, 1,3-dimethylthiourea–1,2-diiodo-3,4,5,6-tetrafluorobenzene (1/1), C 6 F 4 I 2 ·C 3 H 8 N 2 S, 1 , thiourea–1,3-diiodo-2,4,5,6-tetrafluorobenzene (1/1), C 6 F 4 I 2 ·CH 4 N 2 S, 2 , 1,3-dimethylthiourea–1,3-diiodo-2,4,5,6-tetrafluorobenzene (1/1), C 6 F 4 I 2 ·C 3 H 8 N 2 S, 3 , 1,3-dimethylthiourea–1,3-diiodo-2,4,5,6-tetrafluorobenzene–methanol (1/1/1), C 6 F 4 I 2 ·C 3 H 8 N 2 S·CH 4 O, 4 , 1,3-dimethylthiourea–1,3-diiodo-2,4,5,6-tetrafluorobenzene–ethanol (1/1/1), C 6 F 4 I 2 ·C 3 H 8 N 2 S·C 2 H 6 O, 5 , 1,3-dimethylthiourea–1,4-diiodo-2,3,5,6-tetrafluorobenzene (1/1), C 6 F 4 I 2 ·C 3 H 8 N 2 S, 6 , 1,3-dimethylthiourea–1,3,5-trifluoro-2,4,6-triiodobenzene (1/1), C 6 F 3 I 3 ·C 3 H 8 N 2 S, 7 , 1,3-dimethylthiourea–1,1,2,2-tetraiodoethene (1/1), C 6 H 16 N 4 S 2 ·C 2 I 4 , 8 , [(dimethylamino)methylidene](1,2,2-triiodoethenyl)sulfonium iodide–1,1,2,2-tetraiodoethene–acetone (1/1/1), C 5 H 8 I 3 N 2 S + ·I − ·C 3 H 6 O·C 2 I 4 , 9 , 2-amino-4-methyl-1,3-thiazol-3-ium iodide–1,1,2,2-tetraiodoethene (2/3), 2C 4 H 7 N 2 S + ·2I − ·3C 2 I 4 , 10 , and 4,4-dimethyl-4 H -1,3,5-thiadiazine-3,5-diium diiodide–1,1,2,2-tetraiodoethene (2/3), 2C 5 H 12 N 4 S 2+ ·4I − ·3C 2 I 4 , 11 . When utilizing the common halogen-bond-donor molecules 1,2-, 1,3-, and 1,4-diiodotetrafluorobenzene, as well as 1,3,5-trifluoro-2,4,6-triiodobenzene, bifurcated I...S...I interactions were observed, resulting in the formation of isolated rings, chains, and sheets. Tetraiodoethylene (TIE) provided I...S...I cocrystals as well, but further yielded a sulfonium-containing product through the reaction of the S atom with TIE. This particular sulfonium motif is the first of its kind to be structurally characterized, and is stabilized in the solid state through a three-dimensional I...I halogen-bonding network. Thiourea reacted with acetone in the presence of TIE to provide two novel heterocyclic products, again stabilized in the solid state through I...I halogen bonding. 

   more » « less
4. Reductive cleavage of N , N ′-di- tert -butylcarbodiimide generates tert -butylcyanamide ligands, (Me ₃ CNCN) ⁻ , that bind potassium both end-on and side-on in the same single crystal

   https://doi.org/10.1107/S205698902000732X  

   Chung, Amanda B.; Ziller, Joseph W.; Evans, William J. (July 2020, Acta Crystallographica Section E Crystallographic Communications)

   null (Ed.)

   N , N ′-Di- tert -butylcarbodiimide, Me 3 CN=C=NCMe 3 , undergoes reductive cleavage in the presence of the Gd II complex, [K(18-crown-6) 2 ][Gd II (N R 2 ) 3 ] ( R = SiMe 3 ), to form a new type of ligand, the tert -butylcyanamide anion, (Me 3 CNCN) − . This new ligand can bind metals with one or two donor atoms as demonstrated by the isolation of a single crystal containing potassium salts of both end-on and side-on bound tert -butylcyanamide anions, (Me 3 CNCN) − . The crystal contains [K(18-crown-6)(H 2 O)][NCNCMe 3 - kN ], in which one ( t BuNCN) − anion is coordinated end-on to potassium ligated by 18-crown-6 and water, as well as [K(18-crown-6)][η 2 -NCNCMe 3 ], in which an 18-crown-6 potassium is coordinated side-on to the terminal N—C linkage. This single crystal also contains one equivalent of 1,3-di- tert -butyl urea, (C 9 H 20 N 2 O), which is involved in hydrogen bonding that may stabilize the whole assembly, namely, aqua( tert -butylcyanamidato)(1,4,7,10,13,16-hexaoxacyclooctadecane)potassium(I)–( tert -butylcyanamidato)(1,4,7,10,13,16-hexaoxacyclooctadecane)potassium(I)– N , N ′-di- tert -butylcarbodiimide (1/1/1) [K(C 5 H 9 N 2 )(C 12 H 24 O 6 )]·[K(C 5 H 9 N 2 )(C 12 H 24 O 6 )(H 2 O)]·C 9 H 20 N 2 . 

   more » « less
5. The Effect of Runnels on Salt Marsh Sediment Dynamics, Vegetation, and Nitrogen Cycling

   https://doi.org/10.1007/s12237-025-01511-6  

   Sullivan, Hillary_L; Holtzer, Julia; Deegan, Linda_A; Bowen, Jennifer_L (February 2025, Estuaries and Coasts)

   Abstract Runnels, a climate adaptation technique that drains surface water to restore marsh vegetation and habitat, are increasingly being used to prevent the formation of shallow water impoundments or pannes in salt marshes that result in the loss of important ecosystem services. However, we know little about the effect of runnels on salt marsh biogeochemistry. This study measured how sediment characteristics and rates of nitrogen cycle processes were altered by impounded water and vegetation loss, and whether runnels can restore these marsh attributes to reference conditions. Impounded areas were 52 ± 4% less vegetated than nearby intact marsh, with 11 ± 2% less organic matter and 24 ± 5% higher bulk density. Additionally, impoundments removed 32 ± 32 µmol N m⁻²d⁻¹less than reference marsh areas via denitrification. At six of the 11 runneled sites, vegetation percent cover increased by 40 ± 5%, accompanied by a 7 ± 3% recovery of organic matter and a 9 ± 6% reduction of bulk density. At sites where vegetation recovered to within 70% of reference plots at a site, runneled plots removed 97 ± 31 µmol more N m⁻²d⁻¹than impoundments, which was also 82 ± 31 µmol more N m⁻²d⁻¹than reference areas. The driver of recovery is related to initial site conditions, including higher redox potentials and lower porewater salinities, compared with sites where revegetation was unsuccessful. The extent of runnel effectiveness and the recovery of vegetation, sediment characteristics, and nitrogen cycle processes was variable among runneled marshes, and the effectiveness of runnels may depend on initial site-specific characteristics and degree of initial degradation. 

   more » « less