Deciphering the Mechanism of Crystallization of UiO-66 Metal-Organic Framework.

Zirconium-containing metal-organic framework (MOF) with UiO-66 topology is an extremely versatile material, which finds applications beyond gas separation and catalysis. However, after more than 10 years after the first reports introducing this MOF, understanding of the molecular-level mechanism of its nucleation and growth is still lacking. By means of in situ time-resolved high-resolution mass spectrometry, Zr K-edge X-ray absorption spectroscopy, magic-angle spinning nuclear magnetic resonance spectroscopy, and X-ray diffraction it is showed that the nucleation of UiO-66 occurs via a solution-mediated hydrolysis of zirconium chloroterephthalates, whose formation appears to be autocatalytic.

Unraveling the molecular mechanism of MIL-53(Al) crystallization.

The vast structural and chemical diversity of metal-organic frameworks (MOFs) provides the exciting possibility of material's design with tailored properties for gas separation, storage and catalysis. However, after more than twenty years after first reports introducing MOFs, the discovery and control of their synthesis remains extremely challenging due to the lack of understanding of mechanisms of their nucleation and growth. Progress in deciphering crystallization pathways depends on the possibility to follow conversion of initial reagents to products at the molecular level, which is a particular challenge under solvothermal conditions.

Regioselective CF functionalization of ScN@(5)-C.

We report the first synthesis and computational study of ScN@C(CF) - an analog of the previously reported ScN@C(CF) with a less common carbon cage whose chemical properties presently remain far less studied. ScN@C appears to be considerably more reactive toward CF addition than ScN@C and somewhat more reactive than C. Even though the less symmetric (5)-C carbon cage offers far broader opportunities for isomerism than -C, CF addition to ScN@C proceeds regioselectively, similarly to other common fullerene reactions.

Regioselective Synthesis and Characterization of Tris- and Tetra-Prato Adducts of MN@C (M = Y, Gd).

The tris- and tetra-adducts of MN@C metallofullerenes were synthesized and characterized for the first time. The 1,3-dipolar cycloaddition (Prato reaction) of YN@-C and GdN@-C with an excess of -ethylglycine and formaldehyde provided tris- and tetra-fulleropyrrolidine adducts in a regioselective manner. Purification by HPLC and analyses of the isolated peaks by NMR, MS, and vis-NIR spectra revealed that the major products were four tris- and one tetra-isomers for both YN@-C and GdN@-C.

Addition of CF group to endohedral fullerene ScN@I-C.

We report the first successful synthesis of a CF derivative of the stable endohedral fullerene ScN@I-C. Reaction with CFClCOONa yields a single C-symmetric ScN@C(CF) adduct where the CF group is inserted into a [6,6]-bond and opens it to 2.3 Å between the bridgehead carbon atoms.

Structures of GdN@C Prato Bis-Adducts: Crystal Structure, Thermal Isomerization, and Computational Study.

The structures of two bis-ethylpyrrolidinoadducts of GdN@C, obtained by regioselective 1,3-dipolar cycloadditions, were elucidated by single crystal X-ray, visible-near infrared (vis-NIR) spectra, studies on their thermal isomerization, and theoretical calculations. The structure of the minor-bis-adduct reveals a -symmetric carbon cage with [6,6][6,6]-addition sites and with an endohedral GdN cluster that is completely flattened. This is the first example of a crystal structure of GdN@C derivatives.

Site-Selectivity of Prato Additions to C: Experimental and Theoretical Studies of a New Thermodynamic Product at the dd-[5,6]-Junction.

Three Prato monoadduct isomers were synthesized and structurally characterized by H, C NMR spectra and single-crystal X-ray diffraction, and one adduct on the dd-[5,6]-bond was found as the first example of a Prato [5,6]-adduct of C. To investigate the mechanism in the generation of this dd-[5,6]-adduct, computational studies were employed to show that it was thermodynamically obtained by sigmatropic rearrangement from the presumed initial kinetic product de-[6,6]-adduct.

Individual ( A)- and ( C)-Fullerene-Based Nickel(II) Glycinates: Protected Chiral Amino Acids Directly Linked to a Chiral π-Electron System.

Stereoselective electrosynthesis of the first individual ( A)- and ( C)-1,4-fullerene derivatives with a non-inherently chiral functionalization pattern is described, as well as the first example of an optically pure protected primary amino acid directly linked to the fullerene through only the chiral α-amino-acid carbon atom. An application of an auxiliary chiral nickel-Schiff base moiety as derivatizing agent allowed separation of ( A)- and ( C)-1,4-fullerene derivatives using an achiral stationary phase, a separation which has never been done before.

Stepwise Regioselective Hydrogenation of cis-2-C (CF ) Homofullerene with [6,6]-Open/Closed Valence Tautomerism.

The homofullerene compound cis-2-C (CF ) , which has an unusual kind of open/closed valence tautomerism undergoes consecutive regioselective hydrogenation at bridgehead carbon atoms upon reduction with Zn/Cu couple in H O-toluene mixture. The tautomerism barrier in cis-2-C (CF ) is negligible in the neutral state, whereas negative charging both impedes tautomeric transformation and promotes regioselective addition of electrophilic species at the bridgehead carbon atoms. In light of this observation, two novel homofullerene derivatives, mixed [6,6]-open/closed C (CF ) H and [6,6]-open cis-2-C (CF ) H , were synthesized and their structures were unambiguously determined by means of single crystal X-ray crystallography and NMR spectroscopy.

Orienting Effect of the Cage Addends: The Case of Nucleophilic Cyclopropanation of C2 -C70 (CF3 )8.

C2 -C70 (CF3 )8 was found to be a very promising substrate in the Bingel and the Bingel-Hirsch reactions combining perfect regioselectivity with much higher reactivity compared to its analogs. The reactions with diethyl malonate yield a single isomer of the monoadduct C70 (CF3 )8 [C(CO2 Et)2 ] and a single C2 -symmetrical bisadduct C70 (CF3 )8 [C(CO2 Et)2 ]2 . The Bingel-Hirsch variation is particularly interesting in that it additionally affords, in a similar regioselective manner, the unexpected alkylated derivatives C70 (CF3 )8 [CH(CO2 Et)2 ]H and C70 (CF3 )8 [C(CO2 Et)2 ][CH(CO2 Et)2 ]H.

[6,6]-Open and [6,6]-closed isomers of C70(CF2): synthesis, electrochemical and quantum chemical investigation.

Novel difluoromethylenated [70]fullerene derivatives, C70(CF2 )n (n=1-3), were obtained by the reaction of C70 with sodium difluorochloroacetate. Two major products, isomeric C70(CF2 ) mono-adducts with [6,6]-open and [6,6]-closed configurations, were isolated and their homofullerene and methanofullerene structures were reliably determined by a variety of methods that included X-ray analysis and high-level spectroscopic techniques. The [6,6]-open isomer of C70(CF2 ) constitutes the first homofullerene example of a non-hetero [70]fullerene derivative in which functionalisation involves the most reactive bond in the polar region of the cage.