Eugenol, an abundant, naturally occurring phenolic compound, was converted into a thermoplastic polycarbonate by olefin metathesis followed by interfacial polymerization with triphosghene. This resulted in polymers with Mn ranging from 5300-12 700 g mol-1 and an average glass transition temperature (Tg) of 82 degrees C. The polycarbonates were depolymerized via ethenolysis reactions under modest ethylene pressures (150-240 psi) in the presence of [Ru]-metathesis catalysts to yield a discrete monomer [bis(4-allyl-2-methoxyphenol) carbonate, compound 2]. 2 was then polymerized with a second generation Grubbs catalyst (M204) to produce a recycled polymer with Mn = 7500 g mol-1 and a Tg of 114 degrees C. The 32 degrees C increase in Tg was due to the isomerization of the allyl group to internal positions, which then allowed for the formation of stilbene and 3-carbon unsaturated linkages between aromatic groups. To expand the ethenolysis recycling approach to hyperbranched polymers, eugenol was converted into a cyanate ester (3), which was then thermally cyclotrimerized to generate 2,4,6-tris(4-allyl-2-methoxyphenoxy)-1,3,5-triazine (4), a monomer with a triazine core and three pendent aromatic rings with methoxy and allyl substituents. 4 was cross-linked via olefin metathesis (M204 catalyst) to generate a polymer with Mn = 8600 g mol-1 and a Tg of 180 degrees C. Similar to the polycarbonate, the polycyanurate was efficiently depolymerized in the presence of ethylene to regenerate 4. Compound 4 was then polymerized and depolymerized three additional times, demonstrating full circularity for the triazine monomer/polymer. The recycled polymers exhibited similar Tgs (167-184 degrees C) and thermal stability compared to the virgin polymer. Overall, this work demonstrates that both linear and hyperbranched polymers can be readily prepared from eugenol and catalytically recycled under standard ethenolysis conditions. Unlike many conventional methods, the recycled polymers described in this work exhibited no significant degradation in thermomechanical properties. This type of approach supports a circular bioeconomy and may help to reduce plastic waste and the accumulation of micro/nanoplastic particles in the environment.

A challenge facing the synthesis of bioderived platform chemicals such as polyols and polyacids via fermentation processes is their separation from dilute aqueous streams.

The synthesis of molecules with strong coupling between electronic and nuclear spins represents an important challenge in molecular quantum information science. Here, we report the synthesis and characterization of the divalent lutetium metallocene complexes Lu(CpMe5)(CpiPr5) (CpMe5 = pentamethylcyclopentadienyl; CpiPr5 = pentaisopropylcyclopentadienyl), Lu(CpiPr4Et)2 (CpiPr4Et = ethyltetraisopropylcyclopentadienyl), and Lu(CpiPr4)2 (CpiPr4 = tetraisopropylcyclopentadienyl). The molecular structures of these complexes, as determined through single-crystal X-ray diffraction, feature a common bent sandwich geometry, with average Cp-Lu-Cp angles ranging from 159.9° to 152.6°. Analysis of continuous-wave electron paramagnetic resonance (EPR) spectra for the complexes reveals nearly isotropic g tensors with only a slight deviation from that of a free electron. Moreover, an extremely large splitting of the eight-line spectra indicates the presence of strong hyperfine coupling, and simulations provide isotropic hyperfine coupling constants of Aiso = 4.38, 4.30, and 4.17 GHz across the series, where the value of Aiso is found to decrease as the Cp-Lu-Cp angle becomes more acute. Notably, these values are the largest yet observed for any lanthanide complex. Moreover, EPR and computational analysis show that the large values of Aiso stem from large s-orbital character─up to 41.2%─in the corresponding singly occupied molecular orbitals. To our knowledge, this degree of s-character in a molecular orbital is the largest yet reported for an open-shell isolable complex. These results outline a general strategy toward the isolation of paramagnetic molecules with strong hyperfine coupling and highly isotropic doublet electronic ground states.

Boron nitride nanotubes (BNNTs) have great potential as reinforcing agents in polymer composites due to their robust mechanical and thermal properties. BNNT-Polyacrylonitrile (PAN) electrospun composite nanofibers were fabricated with BNNT loadings ranging from 5 to 20 weight percent (wt

Mixed-valence lanthanide complexes of the type (CpiPr5)2Ln2I3 (CpiPr5 = pentaisopropylcyclopentadienyl; Ln = Gd, Tb, Dy, Ho, Er) featuring Ln-Ln bonding interactions can exhibit strongly coupled high-moment ground states with a large axial magnetic anisotropy. Here, we report the synthesis, structures, and magnetic properties of the aryloxido-bridged mixed-valence dilanthanide complexes (CpiPr5)2Ln2(OArtt)3 (1-Ln, Ln = Gd, Dy; -OArtt = 3,5-bis(tert-butyl)phenoxide anion). The solid-state structures of the two complexes are distinct, with 1-Dy exhibiting a nearly symmetric structure and a short Dy-Dy bond of 3.265(1) Å, suggesting valence delocalization, while 1-Gd has an asymmetric structure with each Gd atom in a distinct coordination environment, indicative of valence localization. Static magnetic susceptibility data confirm that 1-Gd is valence localized, with only very weak antiferromagnetic exchange between the GdII and GdIII centers at low temperatures. In contrast, magnetic susceptibility data for 1-Dy reveal strong magnetic coupling to give a large angular momentum ground state with magnetic blocking below 40 K. Solid-state Raman spectra for 1-Dy are indicative of Dy-Dy bonding that persists up to ambient temperatures. Computational analyses suggest that the bonding interaction in 1-Dy becomes highly polarized in the presence of slight structural asymmetry and that this effect becomes more pronounced at higher temperatures, as supported by variable-temperature single-crystal X-ray diffraction data. Detailed exploration of the vibronic coupling is consistent with vibronic-driven valence localization at elevated temperatures in 1-Dy.

Boron nitride nanotubes (BNNT), nanobarbs (BNNB), and nanoparticles (BNNP) were used as photocatalysts under 254 nm UV irradiation for the photodegradation of perfluorooctanoic acid (PFOA). Mass spectrometry was used to monitor PFOA degradation via a stepwise mechanism in which CF2 groups were excised from the parent chain. All BNNM were effective catalysts, with BNNB exhibiting the fastest photodegradation rate, and BNNT showing increased activity upon reuse. The enhanced activity of BNNB and BNNT, along with the ability to incorporate these materials into robust structures, makes them promising candidates for use in the fabrication of photocatalytic filters that can remediate aqueous per- and polyfluoroalkyl substances in flow reactors.

There are a number of different routes for the production of renewable diesel from lipid and crude biomass sources. Most of these approaches generate acyclic hydrocarbons that offer high gravimetric net heats of combustion (NHOC) and good combustion properties, but much lower densities than petroleum-based diesel fuel. To address this shortcoming, biosynthetic farnesene was isomerized with a heterogeneous acid catalyst (Amberlyst-15) under mild conditions and hydrogenated to generate a complex mixture of acyclic, monocyclic, bicyclic, and tricyclic hydrocarbons. The hydrogenated farnesene isomers (HFI) had a density of 0.852 g mL(-1), a gravimetric NHOC of 43.33 MJ kg(-1), a 40 degrees C kinematic viscosity of 3.25 mm(2) s(-1), and a derived cetane number (DCN) of 40. All of these values are similar to or exceed those of diesel fuel derived from petroleum sources. Compared to farnesane, the direct hydrogenation product of farnesene, HFI exhibited 11% higher density and 9% higher volumetric NHOC due to the cyclic compounds contained in the mixture. 10-40% blends of HFI with conventional jet fuel were prepared and exhibited -20 degrees C kinematic viscosities ranging from 4.8-7.8 mm2 s(-1), which fall within the specification for Jet-A (<8.0 mm(2) s(-1)). Overall, acid-catalyzed isomerization of farnesene resulted in an upgraded diesel product that can be easily integrated into current supply chains. This result provides further evidence that hybrid synthetic protocols combining biosynthetic and chemical steps are powerful approaches to the development of next-generation renewable diesel and jet fuels.

A series of dilanthanide benzene inverse sandwich complexes of the type (CpiPr5Ln)2(μ-η6:η6-C6H6) (1-Ln) (Ln = Y, Gd, Tb, Dy, Tm) are reported. These compounds are synthesized by reduction of the respective trivalent dimers CpiPr52Ln2I4 (Ln = Y, Gd, Tb, Dy, Tm) in diethyl ether with potassium graphite in the presence of benzene, and they feature an unusual linear coordination geometry with a highly planar benzene bridge as verified by single-crystal X-ray diffraction. The Ln-Bzcentroid distances of 1-Ln are the shortest distances observed to date, ranging from 1.943(1) Å for 1-Tm to 2.039(6) Å for 1-Gd. Structural, spectroscopic, and magnetic analyses together with density functional theory calculations support the presence of a rare, unsubstituted tetraanionic benzene in each compound, which is stabilized by strong covalent δ bonding interactions involving the filled π* orbitals of (C6H6)4- and vacant dxy and dx2-y2 orbitals of the Ln3+ ions. Notably, 1-Ln are the first examples of compounds of the later lanthanides to feature an unsubstituted tetraanionic benzene.

Mixed-valence dilanthanide complexes of the type (CpiPr5)2Ln2I3 (CpiPr5 = pentaisopropylcyclopentadienyl; Ln = Gd, Tb, Dy) featuring a direct Ln-Ln σ-bonding interaction have been shown to exhibit well-isolated high-spin ground states and, in the case of the Tb and Dy variants, a strong axial magnetic anisotropy that gives rise to a large magnetic coercivity. Here, we report the synthesis and characterization of two new mixed-valence dilanthanide compounds in this series, (CpiPr5)2Ln2I3 (1-Ln; Ln = Ho, Er). Both compounds feature a Ln-Ln bonding interaction, the first such interaction in any molecular compounds of Ho or Er. Like the Tb and Dy congeners, both complexes exhibit high-spin ground states arising from strong spin-spin coupling between the lanthanide 4f electrons and a single σ-type lanthanide-lanthanide bonding electron. Beyond these similarities, however, the magnetic properties of the two compounds diverge. In particular, 1-Er does not exhibit observable magnetic blocking or slow magnetic relaxation, while 1-Ho exhibits magnetic blocking below 28 K, which is the highest temperature among Ho-based single-molecule magnets, and a spin reversal barrier of 556(4) cm-1. Additionally, variable-field magnetization data collected for 1-Ho reveal a coercive field of greater than 32 T below 8 K, more than 6-fold higher than observed for the bulk magnets SmCo5 and Nd2Fe14B, and the highest coercive field reported to date for any single-molecule magnet or molecule-based magnetic material. Multiconfigurational calculations, supported by far-infrared magnetospectroscopy data, reveal that the stark differences in magnetic properties of 1-Ho and 1-Er arise from differences in the local magnetic anisotropy of the lanthanide centers.

A series of alkyl-substituted bicycloheptanes were synthesized by Diels-Alder cycloaddition of cyclopentadiene and C5-C8 alpha-olefins. The reactions were conducted with three equivalents of the alpha-olefin to ensure a high conversion to the cross-coupled product and did not require the use of a solvent or catalyst. The resulting products were then hydrogenated over 10% Pd/C and distilled to yield jet fuel blendstocks. The saturated hydrocarbons exhibited densities ranging from 0.861 to 0.872 g mL(-1) (11.1-12.5% higher than the lower limit for Jet-A), gravimetric net heats of combustion ranging from 42.8 to 43.3 MJ kg(-1) (comparable to Jet-A), and -20 degrees C kinematic viscosities ranging from 5.49 to 18.00 mm(2) s(-1). Cyclopentadiene can be readily derived from crude biomass sources including hemicellulose, while C-5-C-8 olefins can be produced from biomass through Fischer-Tropsch catalysis or oligomerization of bio-based ethylene. Thus, this work provides a route to generate molecularly designed biosynthetic fuels with potential applications as blending agents to increase the performance of sustainable aviation fuels.

Isoamyl alcohol is an important biomass fermentation product that can be used as a gasoline surrogate, jet fuel precursor, and platform molecule for the synthesis of fine chemicals and pharmaceuticals. This study reports on the use of graphene oxide immobilized membra (GOIMs) for the recovery of isoamyl alcohol from an aqueous matrix. The separation was performed using air-sparged membrane distillation (ASMD). In contrast to a conventional PTFE membrane, which exhibited minimal separation, preferential adsorption on graphene oxide within GOIMs resulted in highly selective isoamyl alcohol separation. The separation factor reached 6.7, along with a flux as high as 1.12 kg/m2 h. Notably, the overall mass transfer coefficients indicated improvements with a GOIM. Optimization via response surfaces showed curvature effects for the separation factor due to the interaction effects. An empirical model was generated based on regression equations to predict the flux and separation factor. This study demonstrates the potential of GOIMs and ASMD for the efficient recovery of higher alcohols from aqueous solutions, highlighting the practical applications of these techniques for the production of biofuels and bioproducts.

trans-Nerolidol was quantitatively converted into a stoichiometric mixture of 2-methyl-cyclopentene-1-ol and 2,6-dimethyl-1,5-heptadiene via ring-closing metathesis with a 2nd generation Grubbs-Hoveyda catalyst at 0.03 mol% loading. The alcohol was then converted into tetrahydrodimethyldicyclopentadiene isomers (THDMDCPD) by dehydration, Diels-Alder cycloaddition, and hydrogenation. In parallel, 2,6-dimethyl-1,5-heptadiene was hydrogenated to generate 2,6-dimethylheptane (DMH). A stoichiometric mixture of THDMDCPD and DMH, designated as F1, exhibited outstanding fuel properties including density, gravimetric heat of combustion, and viscosity measurements that met the requirements for Jet-A. In addition, hydrogenation of 2,6-dimethyl-1,5-heptadiene in the presence of a heterogeneous acid catalyst resulted in partial cyclization followed by hydrogenation to yield a mixture containing 70% 2,6-dimethylheptane and 30% 1,1,3-trimethylcyclohexane (F2). F2 exhibited a gravimetric net heat of combustion of 43.69 MJ kg-1 and a kinematic viscosity of only 1.75 mm2 s-1 at -20 degrees C. The remarkable fuel properties of F1 and F2 suggest that they have applications as sustainable aviation fuels or blendstocks with conventional jet fuel. trans-Nerolidol was converted into high-performance sustainable aviation fuel by a combination of ring-closing olefin metathesis, dehydration, and hydrogenation. The fuels exhibited exceptional gravimetic energy density and low viscosity.

Seven different sustainable aviation fuel blends were prepared with hydrocarbons derived from terpenoid precursors. The first, designated as L-Jet, was formulated with various molecules produced from linalool (a terpene alcohol) including hydrogenated methylcyclopentadiene dimers, p-menthane, 2,6-dimethyloctane, and hydrogenated isobutylene trimers. L-Jet was also blended with a synthetic paraffinic kerosene derived from fatty acids and esters (HEFA-Jet) as well as Jet-A. The other four sustainable aviation fuel blends consisted of either Jet-A or HEFA-Jet mixed with cyclic hydrogenated isoprene dimers that can be readily produced from the bio-based hemiterpene, isoprene. To determine the suitability of these blends as surrogates for conventional jet fuel, a number of properties including density, low temperature viscosity, heat of combustion, flashpoint, corrosion, smoke point, conductivity, simulated distillation, existent gum, lubricity, thermal stability, and derived cetane number were measured. The 100 % SAF blends exhibited higher gravimetric heats of combustion and higher smoke points (less soot) compared to the blends with Jet-A. Several of the blends met American Society of Testing and Materials (ASTM) requirements, suggesting that they are promising candidates for certification as next generation aviation fuels.

Three bio-based propargyl ether thermosetting resins with trans-stilbene cores were synthesized from p-coumaric (CD), ferulic (FD), and sinapic (SD) acid, respectively. Differential scanning calorimetry (DSC) analysis of these materials indicated modest processability due to high melting points, short processing windows and large exotherms. To address this issue, a fourth resin with a more flexible bridging group (TD) was synthesized from p-coumaric acid and used as a blending agent. In parallel, CD was photochemically isomerized to the cis-isomer (PD) and blends of CD:PD were prepared. Cross-linked networks derived from the resins exhibited glass transition temperatures (Tgs) ranging from 285-330 degrees C (storage modulus) and char yields from 27-59% at 1000 degrees C under N2. The processable resin blends exhibited exceptional thermal stability due to a higher degree of cross-linking enabled by the structural diversity of the blends. The fire resistance of the networks was evaluated through microscale combustion calorimetry. The networks exhibited heat release capacity (HRC) values ranging from 43-103 J g-1 K-1, which classified them as either non-ignitable or self-extinguishing materials. The results demonstrate that abundant, bio-based hydroxycinnamic acids can serve as platform chemicals for the preparation of thermally stable, fire-resistant networks for aerospace applications. Bio-based propargyl ether thermosetting resins with trans-stilbene cores were synthesized from cinnamic acids. Photochemical isomerization enhanced processability and enabled the fabrication of fire-resistant cross-linked networks.

The actinide elements are attractive alternatives to transition metals or lanthanides for the design of exchange-coupled multinuclear single-molecule magnets. However, the synthesis of such compounds is challenging, as is unraveling any contributions from exchange coupling to the overall magnetism. To date, only a few actinide compounds have been shown to exhibit exchange coupling and single-molecule magnetism. Here, we report triangular uranium(III) clusters of the type (Cp-iPr5)(3)U3X (1-X; X = Cl, Br, I; Cp (iPr5) = pentaisopropylcyclopentadienyl), which are synthesized via reaction of the aryloxide-bridged precursor (Cp (iPr5))(2)U-2(OPh (tBu))(4) with excess Me3SiX. Spectroscopic analysis suggests the presence of covalency in the uranium-halide interactions arising from 5f orbital participation in bonding. The dc magnetic susceptibility data reveal the presence of antiferromagnetic exchange coupling between the uranium(III) centers in these compounds, with the strength of the exchange decreasing down the halide series. Ac magnetic susceptibility data further reveal all compounds to exhibit slow magnetic relaxation under zero dc field. In 1-I, which exhibits particularly weak exchange, magnetic relaxation occurs via a Raman mechanism associated with the individual uranium(III) centers. In contrast, for 1-Br and 1-Cl, magnetic relaxation occurs via an Orbach mechanism, likely involving relaxation between ground and excited exchange-coupled states. Significantly, in the case of 1-Cl, magnetic relaxation is sufficiently slow such that open magnetic hysteresis is observed up to 2.75 K, and the compound exhibits a 100-s blocking temperature of 2.4 K. This compound provides the first example of magnetic blocking in a compound containing only actinide-based ions, as well as the first example involving the uranium(III) oxidation state.

Isoprene was hydrovinylated with a series of alpha-olefins (1-pentene, 1-hexene, 1-heptene, 1-octene) to produce acyclic branched C10-C13 alkenes. The process utilized CoBr2(DPPE) as the precatalyst in loadings as low as 0.1 mol % and zinc as the reducing agent. Use of the cobalt catalyst resulted in primarily 1,4-addition, with carbon coupling at the 4-position of isoprene. A significant amount (-,20%) of the coupling products at the 1-position of isoprene was also observed. Each of the discrete C10, C11, C12, and C13 products were then hydrogenated with 10% Pd/C (200 degrees C; 650 psi H2) to yield jet fuel blendstocks. In addition to the reactions with pure alpha-olefins, an equimolar mixture of the C5-C8 alpha-olefins was used to mimic a stream of olefins produced from ethanol dehydration/oligomerization or Fischer-Tropsch catalysis. The different fuel blends exhibited densities ranging from 0.73 to 0.76 g mL-1, gravimetric net heats of combustion (NHOC) from 43.91 to 44.13 MJ kg-1, and -20 degrees C kinematic viscosities from 2.4 to 6.3 mm2 s-1. The NHOC values were -,2.9% higher than the lower limit for Jet-A, while the low-temperature viscosities were up to 70% lower than the upper limit for Jet-A. In addition to studying the suitability of the lightly branched hydrocarbons generated in this process as jet fuel blendstocks, it was of interest to explore their potential as diesel fuels. The equimolar C10-C13 fuel mixture exhibited a derived cetane number (DCN) of 56, which is 16 units higher than that required for Diesel #2 (40). The outstanding fuel properties of the isoprene-derived fuels suggest that they have applications as replacements for both petroleum-derived Jet-A and Diesel #2.

Highly branched alkanes and cycloalkanes are produced via electrochemical processing of the renewable platform molecule mesityl oxide, which is a dimer of biogenic acetone. The final product is a sustainable, drop-in jet fuel.

This paper demonstrates enhanced removal and recovery of isoprenol by employing nanocarbon-immobilized membranes (NCIM) for air-sparged sweep gas membrane distillation (AS-SGMD). The isoprenol flux, separation factor, and mass transfer coefficient obtained for NCIM were significantly higher compared to plain PTFE membranes under various experimental conditions. Among the two types of nanocarbon-immobilized membranes, namely, graphene oxide-immobilized membrane (GOIM) and carbon nanotube-immobilized membrane (CNIM), GOIM exhibited better performance in terms of isoprenol flux and separation factor. Compared to a plain PTFE membrane, GOIM showed a 71% increase in the isoprenol flux and a 52% increase in the separation factor, achieving a maximum separation factor of 3.6 and flux of 0.68 kg/m2 h at a temperature of 80 degrees C. Enhanced performance of NCIM is attributed to the alteration of the partitioning effect through preferential sorption of the organic moiety, followed by fast desorption from nanocarbon surfaces. The demonstrated enhancements to both membrane flux and isoprenol concentration factor create the potential for significant capital and operational cost savings if such membranes are deployed at a commercial scale.

A series of bisphenols were efficiently prepared from bio-based hydroxycinnamic acids via thermal decarboxylation followed by [Ru]-catalyzed olefin metathesis.

The systematic screening of acceleration factors across a number of small scale confined volume reactors for the accelerated formation of trioximes. Followed by subsequent scale-up of confined volume reactors utilizing thin film methods.