Novel Phthalocyaninatobis(alkylcarboxylato)silicon(IV) Compounds: NMR Data and X‐ray Structures To Study the Spacing Provided by Long Hydrocarbon Tails That Enhance Their Solubility

Abstract

The reaction between trans-PcSiCl2 (1) and the potassium salts of six fatty acids (2 a-2 f) led to the trans-PcSi[OOC(CH2)nCH3]2 compounds (3 a-3 f), which were characterised by elemental analysis, IR, UV/Vis and 1H, 13C, and 29Si NMR spectroscopy. From a detailed study of the NMR spectra, the strong anisotropic currents of the Pc macrocycle were found to have an effect on up to the sixth methylenic group. As expected, the length of the hydrocarbon tail does not affect the chemical shift of the 29Si nucleus of any of the compounds, appearing at around -222.6. The structures of PcSi[OOC(CH2)nCH3]2, where n = 7, 10, 12, 13 and 20, were determined by X-ray crystallography. All the compounds were found to be triclinic with a P1 space group. In all cases the observed crystallographic pseudosymmetry is Ci and the asymmetric unit consists of half a molecule. The silicon atom is at the centre of a distorted octahedron and hence its coordination number is six. The carboxylate fragments are in a trans configuration with respect to the Pc macrocycle. The supramolecular structures are discussed in detail herein. The correlation between the 1H NMR chemical shifts and the position of the corresponding carbon atoms in the hydrocarbon tail reveals that the dicarboxylate substituents exhibit a spacer-like behaviour that enhances the solubility. A detailed study of the tail variable allowed us to evaluate the loss of radial shielding along the Pc2- ligand.

Near-Infrared Fluorescence of Silicon Phthalocyanine Carboxylate Esters

“…Potentially arising from these differing chain orientations, and the resulting presence or absence of steric bulk across the face of the SiPc, the phthalocyanine rings pack with the ring-planes arranged in a parallel fashion in 1 , 2 and 5 , whereas in the rest of the SiPcs they pack in a herringbone pattern, with SiPc planes approximately orthogonal. This pattern of arrangements is not mirrored as closely in other known structures; although those with aryl carboxylates do show packing with orthogonal SiPcs 37 , those with alkyl carboxylates show a mixture of packing motifs, most showing a parallel arrangement of SiPcs 37 , 39 , but some showing herringbone packing 37 , 40 , or other motifs with orthogonally arranged SiPcs 36 , 39 . The intermolecular separation was estimated using the shortest Si···Si distance in each structure.…”

Position of Methyl and Nitrogen on Axial Aryloxy Substituents Determines the Crystal Structure of Silicon Phthalocyanines

“…However, there are only a few publications comprising more than a single crystal structure and systematically investigating the effect of molecular structure on solid-state packing; rare examples of systematic studies include Yang et al producing crystal structures of oligomeric SiPcs with a varying number of repeating units and Marks et al , performing a study on the effect of counterions in doped SiPc films. Sosa-Sánchez et al also investigated the effect of the size of the alkyl tail on solubility and solid-state arrangement of carboxylate SiPcs . All of the aforementioned studies are of large molecules with bulky axial substituents and lack π–π interactions, which is detrimental for electronic functional materials.…”

“…Sosa-Sańchez et al also investigated the effect of the size of the alkyl tail on solubility and solid-state arrangement of carboxylate SiPcs. 19 All of the aforementioned studies are of large molecules with bulky axial substituents and lack π−π interactions, which is detrimental for electronic functional materials. In fact, only a handful of the published structures have axial substituents with less than 10 non-hydrogen atoms allowing for appreciable π−π interactions, but there is no systematic study on the effect of the axial group on the solid-state arrangement.…”

An alkaline one-pot metathesis reaction to give a [Cu3(BTC)2] MOF at r.t., with free Cu coordination sites and enhanced hydrogen uptake properties

“…The presented low temperature, alkaline assisted one-pot strategy employs simple, but well-chosen reagents to obtain a metal-organic framework through a metathesis reaction. [43][44][45][46] The efficient displacing of the reaction course to products in metathesis methodologies has been acquired by two important means: i) phase change (precipitation, neutralization, gasification or combinations of the three) of the products; and ii) generation of products with ionic energy contributions, such as in the formation of inorganic salts. 45 If both i) and ii) metathesis criteria are applied, low temperature, fast, easy and thus efficient chemical transformations are obtained, that could be applicable to a myriad of different chemical procedures.…”