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1.
J Am Chem Soc ; 142(5): 2460-2470, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31896253

RESUMO

Fullerene fragments, referred to as buckybowls, are garnering interest due to their distinctive molecular shapes and optoelectronic properties. Here, we report the synthesis and characterization of a novel C70 subunit, diindeno[4,3,2,1-fghi:4',3',2',1'-opqr]perylene, that is substituted with either triethylsilyl(TES)-ethynyl or 2,4,6-triisopropylphenyl groups at the meta-positions. The resulting compounds (1 and 2) display a bowl-to-bowl inversion at room temperature. Notably, the substituent groups on the meta-positions alter both the geometric and the electronic properties as well as the crystal packing of the buckybowls. In contrast to the 2,4,6-triisopropylphenyl groups in 2, the TES-ethynyl groups in 1 lead to enhanced bond length alternation, resulting in weaker aromaticity of the six-membered rings of the buckybowl skeleton. 1 forms one-dimensional (1D) concave-in-convex stacking columns, and when 1 is blended with C70, the buckybowls encapsulate C70 and result in two-dimensional cocrystals. Organic field-effect transistor (OFET) measurements demonstrate that 1 displays a hole mobility of 0.31 cm2 V-1 s-1, and the 1-C70 cocrystal exhibits ambipolar transport characteristics with electron and hole mobilities approaching 0.40 and 0.07 cm2 V-1 s-1, respectively. This work demonstrates the potential of buckybowls for the development of organic semiconductors.

2.
J Org Chem ; 83(22): 13874-13887, 2018 11 16.
Artigo em Inglês | MEDLINE | ID: mdl-30346768

RESUMO

Enantiomers of a series of tripeptide derivatives with three stereogenic centers (±)-G1-G9 have been prepared from d- and l-α-amino acids as guests for chiral recognition by 1H NMR spectroscopy. In the meantime, a family of tetraaza macrocyclic chiral solvating agents (TAMCSAs) 1a-1d has been synthesized from d-phenylalanine and (1 S,2 S)-(+)-1,2-diaminocyclohexane. Discrimination of enantiomers of (±)-G1-G9 was carried out in the presence of TAMCSAs 1a-1d by 1H NMR spectroscopy. The results indicate that enantiomers of (±)-G1-G9 can be effectively discriminated in the presence of TAMCSAs 1a-1d by 1H NMR signals of multiple protons exhibiting nonequivalent chemical shifts (ΔΔδ) up to 0.616 ppm. Furthermore, enantiomers of (±)-G1-G9 were easily assigned by comparing 1H NMR signals of the split corresponding protons with those attributed to a single enantiomer. Different optical purities (ee up to 90%) of G1 were clearly observed and calculated in the presence of TAMCSAs 1a-1d, respectively. Intermolecular hydrogen bonding interactions were demonstrated through theoretical calculations of enantiomers of (±)-G1 with TAMCSA 1a by means of the hybrid functional theory with the standard basis sets of 3-21G of the Gaussian 03 program.

3.
J Am Chem Soc ; 139(44): 15914-15920, 2017 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-29057655

RESUMO

The straightforward palladium-catalyzed synthesis protocol toward spiro-fused perylene diimides is developed. The reaction involves two palladium-catalyzed C-H activations and 4-fold C-C bond formation sequence from readily available precursors. This facile and step-economic approach also provides another convenient access to ethylene-bridged dimer (NDP) and further π-extended spiro system (SNTP). In addition, the molecular structure of spirodiperylenetetraimide (SDP) is illustrated to show a three-dimensional (3D) cruciform configuration, and its absorbance is distinctly red-shifted due to the significant spiroconjugation effect. With combined properties of broadened and intensive absorption, aligned LUMO levels, and unique molecular geometry, the spiro-fused PDI system represents a new kind of high-performance semiconducting framework as the electron acceptor in high-efficiency organic solar cells.

4.
Org Chem Front ; 3(12): 1716-1724, 2016 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-28191319

RESUMO

1H NMR spectroscopy is often used to discriminate enantiomers of chiral analytes and determine their enantiomeric excess (ee) by various chiral auxiliaries. In reported research, these studies were mainly focused on chiral discriminantion of chiral analytes with only one chiral center. However, many chiral compounds possessing two or more chiral centers are often found in natural products, chiral drugs, products of asymmetric synthesis and biological systems. Therefore, it is necessary to investigate their chiral discrimination by effective chiral auxiliaries using 1H NMR spectroscopy. In this paper, a new class of tetraaza macrocyclic chiral solvating agents (TAMCSAs) with two amide (CONH), two amino (NH) and two phenolic hydroxyl (PhOH) groups has been designed and synthsized for chiral discrimination towards dipeptide derivatives with two chiral centers. These dipeptide derivatives are important chiral species because some of them are used as clinical drugs and special dietary supplements for treatment of human diseases, such as L-alanyl-L-glutamine and aspartame. The results show that these TAMCSAs have excellent chiral discriminating properties and offer multiple detection possibilities pertaining to 1H NMR signals of diagnostic split protons. The nonequivalent chemical shifts (up to 0.486 ppm) of various types of protons of these dipeptide derivatives were evaluated with the assistance of well-resolved 1H NMR signals in most cases. In addition, enantiomeric excesses (ee) of the dipeptide derivatives with different optical compositions have been calculated based on integration of well-separeted proton signals. At the same time, the possible chiral discriminating behaviors have been discussed by means of Job plots, ESI mass spectra and a proposed theoretical model of (±)-G1 with TAMCSA 1c. Additionally, the association constants of enantiomers of (±)-G5 with TAMCSA 1a were calculated by employing the nonlinear curve-fitting method.

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