Cooperative halogen bonding and polarized π-stacking in the formation of coloured charge-transfer co-crystals

Nwachukwu, Chideraa I.; Kehoe, Zachary R.; Bowling, Nathan P.; Speetzen, Erin D.; Bosch, Eric

doi:10.1039/c8nj00693h

Cited by 8 publications

(9 citation statements)

References 39 publications

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“…The most commonly used halogen bond donors have traditionally been neutral organic molecules where a halogen atom is bonded to electron-withdrawing molecular residues. Fluorine atoms [55][56][57][58][59][60], nitro and cyano groups [61][62][63][64][65], or C-C triple bond [16,[66][67][68], exhibit an electron withdrawing effect on the halogen atom and consequently increase the positive electrostatic potential (ESP) of the σ-hole of the halogen atom. The same effect can be archived if the halogen atom is bonded to a more electronegative heteroatom such as nitrogen in N-halogenoimides [69][70][71][72][73][74][75][76] or oxygen in organic hypoiodites [77].…”

Section: Introductionmentioning

confidence: 99%

Halogen Bonding in N-Alkyl-3-halogenopyridinium Salts

Fotović

Stilinović

2021

Crystals

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We performed a structural study of N-alkylated halogenopyridinium cations to examine whether choice of the N-substituent has any considerable effect on the halogen bonding capability of the cations. For that purpose, we prepared a series of N-ethyl-3-halopyridinium iodides and compared them with their N-methyl-3-halopyridinium analogues. Structural analysis revealed that N-ethylated halogenopyridinium cations form slightly shorter C−X⋯I− halogen bonds with iodide anion. We have also attempted synthesis of ditopic symmetric bis-(3-iodopyridinium) dications. Although successful in only one case, the syntheses have afforded two novel ditopic asymmetric monocations with an iodine atom bonded to the pyridine ring and another on the aliphatic N-substituent. Here, the C−I⋯I− halogen bond lengths involving pyridine iodine atom were notably shorter than those involving an aliphatic iodine atom as a halogen bond donor. This trend in halogen bond lengths is in line with the charge distribution on the Hirshfeld surfaces of the cations—the positive charge is predominantly located in the pyridine ring making the pyridine iodine atom σ-hole more positive than the one on the alkyl chan.

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Section: Introductionmentioning

confidence: 99%

Halogen Bonding in N-Alkyl-3-halogenopyridinium Salts

Fotović

Stilinović

2021

Crystals

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“…The compounds 1 and 2 were available from our previous study [ 13 ]. Sonogashira coupling of 1-iodo-3,5-dinitrobenzene with trimethylsilylacetylene followed by base deprotection yielded 3,5-dinitrophenylacetylene [ 12 ]. 3,5-Dinitrophenylacetylene was reacted with a 3-fold excess of 1,3,5-trifluoro-2,4,6-triiodobenzene to form the diiodo dinitrotolane ( 3 ) in 28 % yield shown in Figure 3 .…”

Section: Resultsmentioning

confidence: 99%

“…The cooperativity and competition between the different intermolecular interactions was explored by carrying out single point energy calculations on the relevant clusters from the crystal structure using the Gaussian16 (rev B.01) software program [ 15 ]. All energy calculations were carried out using the M062X-D3 level of theory [ 34 , 35 ] with the DGDZVP basis set [ 32 , 33 ], as used in previous work [ 12 ]. All interaction energies were calculated relative to the unrelaxed monomers and were counterpoise corrected [ 36 , 37 ] for basis set superposition error.…”

Section: Methodsmentioning

confidence: 99%

“… ( a ) Cooperative halogen bonding and EDA π-stacking in cocrystal A•B [ 12 ]. ( b ) Ditopic halogen bonding in cocrystals formed between 5-( N , N -dimethylaminophenylethynylpyrimidine and 1,3-diiodotetrafluorobenzene [ 13 ].…”

Section: Figurementioning

confidence: 99%

“…Clearly, recognition and exploitation of charge-transfer in p-stacked interactions has potential in optoelectronics [ 11 ]. Earlier we described cocrystallization based on cooperative halogen bonding and electron donor-electron acceptor π-complexation to form colored cocrystals [ 12 ]. In that study, which forms the basis for the current report, two complimentary molecules were designed to each include a halogen bonding site and an enhanced electron donor-acceptor π-complexation as illustrated in Figure 1 a.…”

Section: Introductionmentioning

confidence: 99%

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Complementary, Cooperative Ditopic Halogen Bonding and Electron Donor-Acceptor π-π Complexation in the Formation of Cocrystals

et al. 2022

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This study expands and combines concepts from two of our earlier studies. One study reported the complementary halogen bonding and π-π charge transfer complexation observed between isomeric electron rich 4-N,N-dimethylaminophenylethynylpyridines and the electron poor halogen bond donor, 1-(3,5-dinitrophenylethynyl)-2,3,5,6-tetrafluoro-4-iodobenzene while the second study elaborated the ditopic halogen bonding of activated pyrimidines. Leveraging our understanding on the combination of these non-covalent interactions, we describe cocrystallization featuring ditopic halogen bonding and π-stacking. Specifically, red cocrystals are formed between the ditopic electron poor halogen bond donor 1-(3,5-dinitrophenylethynyl)-2,4,6-triflouro-3,5-diiodobenzene and each of electron rich pyrimidines 2- and 5-(4-N,N-dimethyl-aminophenylethynyl)pyrimidine. The X-ray single crystal structures of these cocrystals are described in terms of halogen bonding and electron donor-acceptor π-complexation. Computations confirm that the donor-acceptor π-stacking interactions are consistently stronger than the halogen bonding interactions and that there is cooperativity between π-stacking and halogen bonding in the crystals.

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Evaluation of Halogenopyridinium Cations as Halogen Bond Donors

Fotović

Bedeković

Stilinović

2021

Crystal Growth & Design

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We have performed a database survey and a structural and computational study of the potential and the limitations of halogenopyridinium cations as halogen bond donors. The database survey demonstrated that adding a positive charge on a halogenopyridine ring increases the probability that the halogen atom will participate in a halogen bond, although for chloropyridines it remains below 60%. Crystal structures of both protonated and N -methylated monohalogenated pyridinium cations revealed that the iodo- and bromopyridinium cations always form halogen-bonding contacts with the iodide anions shorter than the sum of the vdW radii, while chloropyridinium cations mostly participate in longer contacts or fail to form halogen bonds. Although a DFT study of the electrostatic potential has shown that both protonation and N -methylation of halogenopyridines leads to a considerable increase in the ESP of the halogen σ-hole, it is generally not the most positive site on the cation, allowing for alternate binding sites.

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Cooperative halogen bonding and polarized π-stacking in the formation of coloured charge-transfer co-crystals

Abstract: Matched electron rich halogen bond acceptors and donor have been synthesized and the halogen bonded charge transfer cocrystals characterized.

Cited by 8 publications

References 39 publications

Halogen Bonding in N-Alkyl-3-halogenopyridinium Salts

Halogen Bonding in N-Alkyl-3-halogenopyridinium Salts

Complementary, Cooperative Ditopic Halogen Bonding and Electron Donor-Acceptor π-π Complexation in the Formation of Cocrystals

Evaluation of Halogenopyridinium Cations as Halogen Bond Donors

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