Porous and Close Packed Supramolecular Assemblies from 2,4-Difluoronitrobenzene with Three Different Linkers and an n-Butylamine Cap

A porous structure formed from sheets with cavities and two close packed structures were crystallised from building blocks prepared from 2,4-difluoronitrobenzene, a diamine linker and n-butylamine. The porous structure crystallised from a flexible building block prepared using 1,4-diaminobutane as linker. The close packed structures were prepared using either piperazine or 1,4-bis(aminomethyl)benzene as a linker and have less conformational freedom.

Amphiphilic Zinc Porphyrin Single-Walled Carbon Nanotube Hybrids: Efficient Formation and Excited State Charge Transfer Studies

Herein, the microscopic and spectroscopic characterization of a novel non-covalent electron donor-acceptor system, in which three different metalloporphyrins (1, 2, and 3) play the dual role of light harvester and electron donor with SWCNTs as electron acceptor, is described. To this end, microscopy, that is, atomic force microscopy (AFM) and transmission electron microscopy (TEM) corroborate the formation of 1-SWCNT, 2-SWCNT, and 3-SWCNT. Spectroscopy by means of Raman, fluorescence, and transient absorption spectroscopy confirmed efficient charge-transfer interaction from photoexcited metalloporphyrins to SWCNTs in the ground and excited state of 1-SWCNT, 2-SWCNT, and 3-SWCNT. The complementary use of spectroelectrochemical and transient absorption measurements substantiates the formation of one-electron oxidized metalloporphyrins after photoexcitation. Multiwavelength global analysis provides insights into the charge-separation and recombination processes in 1-SWCNT, 2-SWCNT, and 3-SWCNT upon photoexcitation. Notably, both the charge-separation and recombination dynamics are fastest in 2-SWCNT. Importantly, the strongest interactions in the steady-state experiments are associated with the fastest excited state decay in the time-resolved measurements.

Computational insight into the halogen bonded self-assembly of hexa-coordinated metalloporphyrins

We demonstrate herein a computational study probing the influence of metalloporphyrins on intermolecular halogen bonding (XB) during supramolecular self-assembly. The results demonstrate that porphyrin aromatic rings can activate or deactivate halogen bonding interactions, especially those on axial ligands, and further influence the preference type of halogen···halogen bonding during the supramolecular self-assembly. Calculations show that the halogen atom present at the equatorial position has a higher sigma hole potential (V_S,max) than that at the axial position. The computational analysis and our observations from the X-ray structure analysis are in good agreement. From structural analysis it is clear that equatorial halogen atoms prefer to participate in Type-II XB interactions whereas the axial halogen atoms either participate in Type-I XB interaction or reluctant to participate in XB interactions due to the decrease of their sigma hole potential. Thus, we demonstrate, herein, for the first time a computational study probing the direct influence of the porphyrin's ring current on the sigma hole potential (V_S,max) of the halogen atoms and subsequently the effects of the supramolecular self-assembly.

Nature of fluorine interactions in ‘wheel and axle’ topology based hexa-coordinated Sn(iv)-porphyrins: an experimental and theoretical analysis

The experimental and theoretical investigations on Sn(iv)-tetrapyridylporphyrins demonstrate that ‘Gulliver effect’ has to be taken into consideration in explaining the genesis of F-based intermolecular interactions.

Straightening out halogen bonds

A new parameter is proposed to quantify the linearity of halogen bonds.

An Organic Zeolite With 10 Å Diameter Pores Assembles From a Soluble and Flexible Building Block by Non-Covalent Interactions

Two similar molecular building blocks, which both contain a hydrogen-bonded nitro group, have been prepared and crystallised. One structure has more flexibility with a butyl side chain which allows an open framework organic zeolite to form with large 10 Å diameter pores, whereas the other structure has less flexibility with an aryl side chain and is close packed. The pore size is comparable with those of the aluminophosphate VPI-5 (12 Å). It is concluded that some flexibility in the design of the building block for porous organic molecular materials was beneficial.

Phase transition in polar 2-nitroanilinium nitrate. Graph-set approach of hydrogen bonding patterns and analysis of vibrational spectra

A phase transition in new compound 2-nitroanilinium nitrate, (H2NA)NO₃, was found. A symmetry lowering from orthorhombic, Pmn2₁, to monoclinic one, P2₁, at 249 K is observed. During the phase transition, the H2NA⁺ and nitrate ions displace from the mirror plane in high-temperature phase. As a result, hydrogen bonding network constructed by the ammonio group and NO₃^- anion is changed. Especially, a bifurcated hydrogen bond disappears. Mathematical operations using both elementary and hydrogen bond graph-set descriptors were used for the first time to describe a mechanism of phase transition. Changes in hydrogen bonding network were also studied by means of vibrational spectroscopy. Band shift associated with stretching and bending vibrations of the ammonio group indicates that the energy of intermolecular interactions rises along with temperature decrease. SHG response for the studied compound is higher than KDP, I_(H2NA)NO3 = 1.1·I_KDP, although a decay of the signal was observed due to instability of the sample.

Wheel-and-axle topology-driven halogen bonds: formation of ladder, 1D and 2D networks in hexa-coordinated Sn(iv) porphyrins

Wheel-and-axle topology-driven halogen bonded supramolecular networks in six-coordinated Sn(iv)-porphyrins.

Sensing of diclofenac by a porphyrin-based artificial receptor

The synthesis of a porphyrin chemosensor is here reported as well as its sensing activity in detecting the emerging pollutant diclofenac with an overall 1 : 1 binding constant of about 10⁵ M⁻¹.

Supramolecular frameworks based on 5,10,15,20-tetra(4-carboxyphenyl)porphyrins

Hydrogen bonding is used to prepare porphyrin-containing supramolecular frameworks.

Controllable morphology and self-assembly of one-dimensional luminescent crystals based on alkyl-fluoro-substituted dithienophenazines

A class of dithienophenazine derivatives, 9,10-difluoro-2,5-dialkyldithieno[3,2-a:2′,3′-c]phenazine (F-n, n = 4, 5, 6, 7 and 8), modified with various lengths of linear alkyl chains were synthesized and used as building blocks to assemble luminescent one-dimensional (1D) nano/microcrystals.

Novel meso-substituted trans-A2B2 porphyrins: synthesis and structure of their metal-mediated supramolecular assemblies

Five novel trans-A₂B₂ porphyrins and their corresponding coordination polymers with transition metals have been synthesized. Absorption and emission studies and structural investigations define the coordination patterns of these compounds in the solid state.

A supramolecular self-assembly host–guest system from cyclodextrin as an absolute water-soluble fluorescence sensor for aluminium ions: synthesis, characterization and sensing activity

In the study, an organic molecule derived from paeonol and anthraniloyl hydrazine (L) was synthesized via a Schiff-base reaction.