Alkali‐Metal Trichloroacetates for Dichloromethylenation of Fullerenes: Nucleophilic Addition‐Substitution Route

The first experimental evidence that fullerenes react with alkali‐metal trichloroacetates through a nucleophilic addition‐substitution route, yielding dichloromethylenefullerenes as the final products, is reported. The intermediates, C₆₀(CCl₃)^? and C₇₀(CCl₃)^? anions, have been isolated in their protonated forms as ortho‐C₆₀(CCl₃)H, as well as three ortho and one para isomer of C₇₀(CCl₃)H. The structures were unambiguously determined by means of ¹H, ¹³C, and ¹H–¹³C HMBC NMR spectroscopy along with UV/Vis spectroscopy. The observed regiochemistry was analyzed with the aid of quantum chemical calculations. Conversion of the protonated compounds into the [6,6]‐closed C_60/70(CCl₂) cycloadducts under basic conditions can be effected only for the ortho isomers, whereas para‐C₇₀(CCl₃)H decomposes back into pristine C₇₀.     

Entrapped bonded hydrogen in a fullerene: the five-atom cluster Sc3CH in C80.

The synthesis and characterisation of the new endohedral cluster fullerene Sc(3)CH@C(80) is reported. The encapsulation of the first hydrocarbon cluster inside a fullerene was achieved by the arc burning method in a reactive CH(4) atmosphere. The extensive characterisation by mass spectrometry (MS), high- pressure liquid chromatography (HPLC), (45)Sc NMR, electron spin resonance (ESR), UV/Vis-NIR and Raman spectroscopy provided the experimental evidence for the caging of the five-atom Sc(3)CH cluster inside the C(80) cage isomer with icosahedral symmetry. The proposed new structure was confirmed by DFT calculations, which gave a closed shell and large energy gap structure. Thus a pyramidal Sc(3)CH cluster and the I(h)-C(80) cage were shown to be the most stable configuration for Sc(3)CH@C(80) whereas alternative structures give a smaller bonding energy as well as a smaller energy gap.     

Seven-minute synthesis of pure C(s)-C60Cl6 from [60]fullerene and iodine monochloride: first IR, Raman, and mass spectra of 99 mol % C60Cl6

Three previously reported procedures for the synthesis of pure C(s)-C60Cl6 from C60 and ICl dissolved in benzene or 1,2-dichlorobenzene were shown to actually yield complex mixtures of products that contain, at best, 54-80% C(s)-C60Cl6 based on HPLC integrated intensities. MALDI mass spectrometry was used for the first time to identify other components of the reaction mixtures. An improved synthetic procedure was developed for the synthesis of about 150 mg batches of chlorofullerenes containing 90% C(s)-C60Cl6 based on HPLC intensities. The optimum reaction time was decreased from several days to seven minutes. Small amounts of the product were purified by HPLC (toluene eluent) to 99% purity. The pure compound C(s)-C60Cl6 is stable for at least three months as a solvent-free powder at 25 degrees C. The Raman, far-IR, and MALDI mass spectra of pure C(s)-C60Cl6 are reported for the first time. The Raman and far-IR spectra, the first reported for any C60Cl(n) chlorofullerene, were used to carry out a vibrational analysis of C(s)-C60Cl6 at the DFT level of theory.     

Synthesis and structural characterization of highly chlorinated C70, C70Cl28

Chlorination of [70]fullerene with SbCl(5), VCl(4) or PCl(5) yielded C(70)Cl(28) comprising three isomers, all containing four isolated benzenoid rings in the fullerene cage. This demonstrates, for the first time for C(70) derivatives, a stabilization effect due to planar aromaticity.     

Synthesis of Prebiotic Glycerol in Interstellar Ices

Contemporary mechanisms for the spontaneous formation of glycerol have not been able to explain its existence on early Earth. The exogenous origin and delivery of organic molecules to early Earth presents an alternative route to their terrestrial in situ formation since biorelevant molecules like amino acids, carboxylic acids, and alkylphosphonic acids have been recovered from carbonaceous chondrites. Reported herein is the first in situ identification of glycerol, the key building block of all cellular membranes, formed by exposure of methanol‐based — interstellar model ices to ionizing radiation in the form of energetic electrons. These results provide compelling evidence that the radiation‐induced formation of glycerol in low‐temperature interstellar model ices is facile. Synthesized on interstellar grains and eventually incorporated into the “building material” of solar systems, biorelevant molecules such as glycerol could have been dispensed to habitable planets such as early Earth by comets and meteorites.     

Synthesis and structural characterization of novel pyranoluteolinidin dyes

The synthesis and structural characterization by LC–MS and NMR of novel pyranoluteolinidin derivatives are reported. The compounds result from the reactions between luteolinidin and three different carboxylic acids in wine model-like solutions. The three pigments possess different substituents attached to the D ring (methyl, catechol and dimethylaminophenyl groups) and the same catechol group in the B ring, yielding a wide spectrum of colors from yellow to pink-purple.     

Orientational dynamics of C70 molecules in chlorobenzene

Dynamics of anisotropy relaxation of C₇₀ singlet excited molecules in chlorobenzene was measured at room temperature by the picosecond transient grating technique. The time-ependent diffraction efficiency exhibits a two-stage decay: a fast component (₁ = 12±5 ps), which is comparable with the corresponding signal of C₆₀ in chlorobenzene ( = 8±2 ps), and a slow one (₂ = 30±5 ps). It is supposed that relaxation of anisotropy is related to the orientational mobility of excited C₇₀ molecules relative to two axes of the molecular framework. The results obtained cannot be described by the Einstein-Stokes-Debye theory. The Hynes-Kapral-Weinberg theory, which takes into account microscopic interactions between molecules upon collisions, agrees satisfactorily with the experiment. The influence of dielectric friction on the orientational mobility of C₇₀ in chlorobenzene was estimated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 601–604, March, 1996.     

Synthesis and structural characterization of amino-functionalized polysaccharides

A variety of carbohydrates, in particular polysaccharides can be subjected to chemical modification to obtain derivatives with amphiphilic properties, which enable biochemical or biological reactions at the polymer surface. In the present work, a polydisperse maltodextrin mixture of average molecular weight 3000 was coupled with 1,6-hexamethylenediamine (HMD) via reductive amination reaction. Resulting products were characterized by thermal analysis and positive nanoelectrospray quadrupole time-of-flight (Q-TOF) mass spectrometry (MS) and tandem mass spectrometry (MS/MS). Both thermal analysis and MS screening confirmed the formation of the HMD-polysaccharide coupling products. Moreover, HMD-linked polysaccharide chains containing 2 to 26 glucose building blocks were identified by nanoESI Q-TOF MS. MS/MS fragmentation using collision-induced dissociation (CID) at low ion acceleration energies provided strong evidence for HMD-maltodextrin linkage formation and the set of sequence ions diagnostic for the composition and structure of a HMD-linked chain containing 18 glucose residues.      

Highly Efficient Synthesis of Globular (Bola)amphiphilic [5:1]Hexakisadducts of C60

We report on the very facile access of a new family of amphiphilic and bola‐amphiphilic fullerene [5:1]hexakisadducts 9 a – f and 11 a – e . The key point for this successful approach is the use of C_2v‐symmetrical fullerene pentakisadduct precursors 2 b – f allowing for the completely regioselective addition of a sixth malonate addend to complete the octahedral [5:1] addition pattern. For the synthesis of the new amphiphiles we first developed a new second‐generation dendrimer containing 9 tert‐butoxycarbonyl (Boc)‐protected amino functions at the periphery and two new malonates containing 6 or 18 Boc‐protected amino termini, respectively. The hexakisadducts contain up to 18 positive or negative charges at the dendritic moiety and either no or ten positive or negative charges at the unbranched malonate positions after deprotection with trifluoroacetic acid (TFA). The charge state at the termini is pH‐dependent. Complete structural characterization of the new compounds was carried out by ESI mass spectrometry and by UV/Vis, FTIR, ¹H NMR and ¹³C NMR spectroscopy. We were also able to obtain the first X‐ray crystal structure of pentakisadduct ( 2 a ) with a C_2v‐symmetrical addition pattern. The new amphiphilic hexakisadducts show interesting solubility properties in water. Initial investigations on the aggregation properties of the amphiphilic hexakisadduct 12 c by using dynamic light scattering (DLS) and conductivity measurements, show aggregates with a radius up to 200 nm and a critical micelle concentration (CMC) of approximately 8 mg L^?1.     

Synthesis and characterization of cellulose resins

A series of cellulose-phenol-formaldehyde (LCPF) and cellulose-urea-formaldehyde (CUF) resins were produced using banana waste. Detailed structure and quantitative information was provided by FT-IR and mass spectroscopy. The main interests were the ability to use banana waste as a source of cellulose in the condensation reaction. Functionality of CPF and structure of CUF were investigated. Copyright © 2003 John Wiley & Sons, Ltd.     

The extended view on the empty C2(3)-C82 fullerene: isolation, spectroscopic, electrochemical, and spectroelectrochemical characterization and DFT calculations

An extended study of the spectroscopic and redox properties of the C(82) fullerene is presented. Among the nine isolated-pentagon-rule (IPR) isomers of the C(82) fullerene the C(82)(3) isomer with C(2) symmetry is the only stable, empty fullerene structure formed in the arc burning process that can be isolated in an isomerically pure form. Here, its formation and isolation are described and its structure is confirmed by experimental spectroscopic studies as well as time-dependent DFT calculations. The electrochemistry of the C(82)(3) isomer is studied in detail by cyclic voltammetry and spectroelectrochemistry. The anionic species of C(82) with the charge ranging from C(82) (-) to C(82) (4-) were successively generated in o-dichlorobenzene solution at room temperature and characterized by in situ ESR and visible/near-infrared (Vis/NIR) spectroscopy. The data give new insights into the charged states of the C(82)(3) fullerene.     

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(CO₂Et)₂] and a single C₂‐symmetrical bisadduct C₇₀(CF₃)₈[C(CO₂Et)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(CO₂Et)₂]H and C₇₀(CF₃)₈[C(CO₂Et)₂][CH(CO₂Et)₂]H. The novel compounds have been isolated and structurally characterized by means of ¹H and ¹⁹F NMR spectroscopy as well as single‐crystal X‐ray diffraction. The mechanistic and regiochemical aspects of the reaction are explained with the aid of DFT calculations.     

C2 isomers of C84F40 and C84F44 are cuboid and contain benzenoid and naphthalenoid aromatic patches

A 1:1 mixture of C84F40 and C84F44, both derived from the D2(IV) isomer, has been isolated from the fluorination of [84]fullerene with either MnF3 or CoF3 at 500 degrees C. The 1D and 2D COSY 19F NMR spectra showed that each derivative is cuboid, having benzenoid rings at four of the six octahedral sites; the two remaining sites have naphthalenoid rings for C84F40, and two slightly offset benzenoid rings for C84F44. The benzenoid rings each have six adjacent sp3-hybridised carbon atoms whilst the naphthalenoid moieties have eight, thus facilitating full delocalisation. In terms of the number and size of aromatic patches, C84F44 is the most aromatic fullerene derivative yet isolated.