The development of a comprehensive toolbox based on multi-level,high-throughput screening of MOFs for CO/N2 separations

The separation of CO/N₂ mixtures is a challenging problem in the petrochemical sector due to the very similar physical properties of these two molecules, such as size, molecular weight and boiling point. To solve this and other challenging gas separations, one requires a holistic approach. The complexity of a screening exercise for adsorption-based separations arises from the multitude of existing porous materials, including metal–organic frameworks. Besides, the multivariate nature of the performance criteria that needs to be considered when designing an optimal adsorbent and a separation process – i.e. an optimal material requires fulfillment of several criteria simultaneously – makes the screening challenging. To address this, we have developed a multi-scale approach combining high-throughput molecular simulation screening, data mining and advanced visualization, as well as process system modelling, backed up by experimental validation. We have applied our recent advances in the engineering of porous materials'' morphology to develop advanced monolithic structures. These conformed, shaped monoliths can be used readily in industrial applications, bringing a valuable strategy for the development of advanced materials. This toolbox is flexible enough to be applied to multiple adsorption-based gas separation applications.

The separation of challenging mixtures through adsorption is a multidimensional problem that requires a holistic approach. Our toolbox combines experiments, molecular and process simulations with data visualization to find optimal, porous materials.     

Cyclopolymerization of amine-linked diacrylate monomers

New diacrylate monomers for cyclopolymerization were synthesized from the reaction of ethyl α-chloromethylacrylate (ECMA) and t-butyl α-bromomethyl acrylate (TBBr) with aniline, adamantyl amine, t-butyl amine, cyanamide, and 4-tetradecyl aniline in yields of ca. 50–70%. Bulk and solution polymerizations with azobisisobutyronitrile (AIBN) at 60–85°C gave soluble cyclopolymers with M_n and M_w ranging from 10,000–30,000 and 12,000–40,000, respectively. The ECMA–cyanamide derivative only gave crosslinked polymers. ¹H and ¹³C solution NMR indicated high cyclization efficiency (>93%). A prototype NLO polymer was synthesized from the reaction of the TBBr–aniline cyclopolymer with tetracyanoethylene. The p-hydroxyaniline derivative of ECMA was synthesized and used for further derivatizations; for example, the benzoate ester was made and polymerized (M_n = 21,260 and M_w = 40,317). The ester groups of the TBBrndash;aniline polymer were hydrolyzed completely to give a polymer with both acid and base moieties. DSC thermograms showed glass transitions of 132°C for the ECMA–aniline derivative, 192°C for the ECMA–adamantyl derivative, 53°C for the TBBr–tetradecylaniline derivative, and 120° for the ECMA–p-benzoylaniline derivative. The ECMA–t-butyl amine polymer showed no obvious T_g. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2111–2121, 1997     

Nucleophilic Addition to CC Bonds,Part X

A mechanistic model is presented for the base‐catalyzed intramolecular cyclization of polycyclic unsaturated alcohols of type A to ethers D (Scheme 1). The alkoxide anion B is formed first in a fast acid‐base equilibrium. For the subsequent reaction to D , a carbanion‐like transition state C is proposed. This mechanism is in full agreement with our results regarding the influence of substituents on the regioselectivity and the rate of cyclization. We studied the effect of alkyl substituents in allylic position (alkylated endocylic olefinic alcohols 1 – 3 ) and, especially, at the exocyclic double bond ( 12 – 15 ). The fastest cyclization (k_rel=1) is 12 → 16 , which proceeds via a primary carbanion‐like transition state ( E : R¹=R²=H). The corresponding processes 13 → 17 and 14 → 17 are characterized by a less‐stable secondary carbanion‐like transtition state ( E : R¹=Me, R²=H, or vice versa) and are slower by a factor of 10⁴. The slowest reaction (k_rel ca. 10⁻⁶) is the cyclization 15 → 18 via a tertiary carbanion‐like transition state ( E : R¹=R²=Me).     

Nucleophilic Additions to Unactivated Carbon-Carbon Double Bonds. Base-Catalysed Ether Formation. Preliminary Communication

Several examples (3 → 5, 4 → 7, 6 → 7, 9 → 10) of base-catalysed intramolecular ether formation involving nucleophilic attack on an unactivated carbon-carbon double bond are described.     

1,7-Trimethylenenorbornane. A novel member of the ‘adamantaneland’. Preliminary communication

A synthesis of the novel C₁₀H₁₆ hydrocarbon 1,7-trimethylenenorbornane ( 13 ), one of the 19 members of the adamantane family, is described.     

An ab initio study of O2 and CO2 transport by perfluorocarbons

Fluorocarbons have been successfully applied as oxygen carriers replacing blood. In order to understand the nature of the interaction between fluorocarbons and hydrocarbons on the one hand and O₂, N₂ and CO₂ on the other, STO-3G calculations have been performed on their complexes. The very slight energies of interaction that were obtained seem to substantiate the contention that O₂, N₂ and CO₂ are physically dissolved in fluorocarbons. This energy of interaction is, however, distinctly larger for fluorocarbons than for hydrocarbons. Electrostatic potentials have been computed around several fluorocarbons. They make it possible to predict the geometries of the complexes that are formed.     

Two-dimensional electrophoresis investigation of short-term response of flax seedlings to a cold shock

The flax, Linum usitatissimum L., is particularly suitable for studying the transduction and long-term signal storage of environmental signals. To investigate the underlying molecular mechanisms, we have focused on the initial changes in the proteome since these offer the possibility of reflecting the plant's history of exposure to stress. In principle, this 'proteome signature' might be revealed by two-dimensional electrophoresis (2-DE). We have therefore determined the potential of 2-DE to study the kinetics of changes to the proteome of flax induced by a 1 min cold shock. Protein identification is difficult with flax because of the lack of knowledge of gene sequences. Nevertheless, 2-DE analysis can be informative providing the significance of changes can be evaluated. We have developed a stringent threshold method to determine the significance of changes in gels obtained with proteins extracted from hypocotyls at different times after cold shock. This allowed us to reliably detect and characterize the kinetics of a set of seven spots that responded to cold shock and that constitute candidates for a proteome signature of long-term signal storage.     

Heterodiamantane und strukturell verwandte Verbindungen. III.. Pentacyclische diäther der C11-reihe. 5, 13-Dioxapentacyclo-[6.5.0.02,6.03,12.04,9]tridecan, 4, 13-dioxapentacyclo [6.4.1.02,7.03,10.05,9]tridecan und 3, 10-dioxapentacyclo [7.3.1.02,7.04,12.06,11]tridecan

Heterodiamantanes and Structurally Related Compounds. Part III. The Pentacyclic C₁₁-Diethers 5, 13-Dioxapentacyclo [6.5.0.0^2,6.0^3,12.0^4,9]tridecane, 4, 13-Dioxapentacyclo [6.4.1.0^2,7.0^3,10.0^5,9]tridecane, and 3, 10-Dioxapentacyclo [7.3.1.0^2,7.0^4,12.0^6,11]tridecane In connection with the studies on heterodiamantanes and structurally related compounds the three novel pentacyclic diethers 3 – 5 were prepared starting from the cyclopentadienone dimer 6 . All four compounds have as common features a central carbocyclic 6-membered ring with four axial alkyl substituents and two oxygen functions in 1, 4 position. The required eleventh C-atom was introduced by dichlorocarbene addition either to 6 ( → 7 ) (Scheme 2) or to 29 ( → 28 ) (Scheme 4). Diether 3 was obtained by reduction of 26 (Scheme 2), a suitable precursor prepared either by intramolecular addition ( 24 → 26 ; Scheme 2) or substitution ( 30 → 26 , 31 → 26 ; Scheme 4), as well as by direct substitution ( 44 → 3 , 42 → 3 ; Scheme 5). Diether 4 was the product of a direct substitution ( 39 → 4 , 36 → 4 ; Scheme 5). The synthesis of diether 5 was achieved from the addition product 51 (resulting from the alcohols 47 and 48 ; Scheme 6). Diether 4 is the thermodynamically least stable of the three diethers 3 – 5 . It was easily isomerized to 5 on treatment with concentrated sulfuric acid in benzene whereas 3 and 5 remained unchanged under these conditions.     

The Aluminum-Bromide-Catalyzed Adamantane Rearrangement of syn- and anti-Tricyclo[4.2.1.12,5]decane

In the presence of AlBr₃ in CS₂ at temperatures below 0°, syn-tricyclo[4.2.1.1^2,5]decane ( 1 ) isomerizes exclusively to anti-tricyclo[4.2.1.1^2,5]decane ( 2 ) at a higher rate than the latter rearranges to 2-exo,3-exo-trimethylene-8,9,10-trinorbornane ( 4 ). However, at temperature above 0°, the anti-isomer 2 isomerizes to 4 faster than 1 to 2 and 4 . As a consequence, hydride abstraction occurs at C(3) (→carbocation a , which rearranges to carbocation b (anti-skeleton)) in the syn-isomer 1 , and more readily at C(9) (→carbocation c ) than at C(3) (→carbocation b ) in the anti-isomer 2 .     

Nucleophilic Addition to C,C-Double Bonds. IV. Ether formation by intramolecular addition to unsymmetrically alkyl-substituted C,C-double bonds

Tricyclic olefinic alcohols containing an unsymmetrically alkyl-substituted C, C-double bond were cyclized intramolecularly to their corresponding ethers under basic conditions: 9 → 12 , 10 → 17 + 18 , and 11 → 12 (Scheme 3, Table 1). The reactivity is mainly due to relieve of ground state strain. Alcohol 9 (endocyclic double bond) isomerized under intramolecular assistance by the hydroxyl group to 11 (exocyclic double bond) before cyclization to 12 occurred (Scheme 5). The latter step being the faster one, no isomerization 11 → 9 was observed.