Renjie Li

Cyclophanes of Perylene Tetracarboxylic Diimide with Different Substituents at Bay Positions

Cyclophanes of perylene tetracarboxylic diimides (PDIs) with different substituents at the bay positions, namely four phenoxy groups at the 1,7-positions (1), four piperidinyl groups at the 1,7-positions (2), and eight phenoxy groups at the 1,6,7,12-positions (3) of the two PDI rings, have been synthesized by the condensation of perylene dianhydride with amine in a dilute solution. These novel cyclophanes were characterized by (1)H NMR spectroscopy, MALDI-TOF mass spectrometry, electronic absorption spectroscopy, and elemental analysis. The conformational isomers of cyclophanes substituted with four piperidinyl groups at the 1,7-positions (2 a and 2 b) were successfully separated by preparative TLC. The main absorption band of the cyclophanes shifts significantly to the higher energy side in comparison with their monomeric counterparts, which indicates significant pi-pi interaction between the PDI units in the cyclophanes. Nevertheless, both the electronic absorption and fluorescence spectra of the cyclophanes were found to change along with the number and nature of the side groups at the bay positions of the PDI ring. Time-dependent DFT calculations on the conformational isomers 2 a and 2 b reproduce well their experimental electronic absorption spectra. Electrochemical studies reveal that the first oxidation and reduction potentials of the PDI ring in the cyclophanes increase significantly compared with those of the corresponding monomeric counterparts, in line with the change in the energy of the HOMO and LUMO according to the theoretical calculations.

Nonperipherally Octa(butyloxy)‐Substituted Phthalocyanine Derivatives with Good Crystallinity: Effects of Metal–Ligand Coordination on the Molecular Structure, Internal Structure, and Dimensions of Self‐Assembled Nanostructures

To investigate the effects of metal-ligand coordination on the molecular structure, internal structure, dimensions, and morphology of self-assembled nanostructures, two nonperipherally octa(alkoxyl)-substituted phthalocyanine compounds with good crystallinity, namely, metal-free 1,4,8,11,15,18,22,25-octa(butyloxy)phthalocyanine H(2)Pc(alpha-OC(4)H(9))(8) (1) and its lead complex Pb[Pc(alpha-OC(4)H(9))(8)] (2), were synthesized. Single-crystal X-ray diffraction analysis revealed the distorted molecular structure of metal-free phthalocyanine with a saddle conformation. In the crystal of 2, two monomeric molecules are linked by coordination of the Pb atom of one molecule with an aza-nitrogen atom and its two neighboring oxygen atoms from the butyloxy substituents of another molecule, thereby forming a Pb-connected pseudo-double-decker supramolecular structure with a domed conformation for the phthalocyanine ligand. The self-assembling properties of 1 and 2 in the absence and presence of sodium ions were comparatively investigated by scanning electronic microscopy (SEM), spectroscopy, and X-ray diffraction techniques. Intermolecular pi-pi interactions between metal-free phthalocyanine molecules led to the formation of nanoribbons several micrometers in length and with an average width of approximately 100 nm, whereas the phthalocyaninato lead complex self-assembles into nanostructures also with the ribbon morphology and micrometer length but with a different average width of approximately 150 nm depending on the pi-pi interactions between neighboring Pb-connected pseudo-double-decker building blocks. This revealed the effect of the molecular structure (conformation) associated with metal-ligand (Pb-N(isoindole), Pb-N(aza), and Pb-O(butyloxy)) coordination on the dimensions of the nanostructures. In the presence of Na(+), additional metal-ligand (Na-N(aza) and Na-O(butyloxy)) coordination bonds formed between sodium atoms and aza-nitrogen atoms and the neighboring butyloxy oxygen atoms of two metal-free phthalocyanine molecules cooperate with the intrinsic intermolecular pi-pi interactions, thereby resulting in an Na-connected pseudo-double-decker building block with a twisted structure for the phthalocyanine ligand, which self-assembles into twisted nanoribbons with an average width of approximately 50 nm depending on the intertetrapyrrole pi-pi interaction. This is evidenced by the X-ray diffraction analysis results for the resulting aggregates. Twisted nanoribbons with an average width of approximately 100 nm were also formed from the lead coordination compound 2 in the presence of Na(+) with a Pb-connected pseudo-double-decker as the building block due to the formation of metal-ligand (Na-N(aza) and Na-O(butyloxy)) coordination bonds between additionally introduced sodium ions and two phthalocyanine ligands of neighboring pseudo-double-decker building blocks.

Synthesis, spectroscopic properties, and electrochemistry of heteroleptic rare earth double-decker complexes with phthalocyaninato and meso-tetrakis (4-chlorophenyl)porphyrinato ligands

A series of fourteen heteroleptic (phthalocyaninato)(porphyrinato) rare earth(III) double-decker complexes, [MIII(Pc)(TClPP)] n [M=Y, La–Lu except Ce and Pm; Pc=phthalocyaninate; TClPP=meso-tetrakis(4-chlorophenyl)porphyrinate] has been prepared by base-promoted cyclization of phthalonitrile on the corresponding [MIII(TClPP)(acac)] n (acac=acetylacetonate) as the template in refluxing n-octanol. The yields are highest for the mid-lanthanides, which have the optimum size to balance the stabilization due to π-π interactions and the destabilization due to axial compression of the two π systems. The whole series of double-decker complexes has been characterized by elemental analysis and a wide range of spectroscopic methods. The molecular structure of [GdIII(Pc)(TClPP)] has also been determined. All the electronic absorption bands are dependent on the size of the metal center, suggesting that all the transitions involve molecular orbitals with contributions from both Pc and TClPP ligands. This has been supported by a systematic investigation of the electrochemical properties of the whole series of complexes. All these studies indicate that there are substantial π-π interactions and the hole is mainly localized at the Pc ligand.