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The nanoscale host–guest interactions between [n]cycloparaphenylene ([n]CPP; n = 10, 8 and 9) nano-ring and fullerene C60 were explored theoretically. It is found that relatively small variations in the sizes of the [n]CPP host lead to very significant changes in encapsulation property toward the fullerene C60 guest. Expectedly, one stable inclusion-configuration of [10]CPP⊃C60 and one floating-configuration of [8]CPP⊃C60 are located on the potential surfaces of the two complexes, respectively. Unexpectedly, besides a floating-configuration (F-[9]CPP⊃C60), another stable inclusion-configuration (I-[9]CPP⊃C60) is also located on the potential surface of [9]CPP⊃C60 host–guest complex. Interaction energies and natural steric analysis show that these complexes are stabilized by balancing concave–convex π–π attractive and steric repulsive host–guest interactions. In contrast, the steric repulsive energy (Es) between host and guest of I-[9]CPP⊃C60 is as high as 233.12 kJ mol−1, which is much larger than those in other complexes. The movements of C60 guest through the cavities of [n]CPP host (n = 10, 8 and 9) are simulated by calculating the energy profile, and the results interestingly reveal that the encapsulation of C60 by [10]CPP is in the manner of a single-potential well, by [8]CPP in the manner of a double-potential well, and by [9]CPP in the special manner of a three-potential well. We predict that the movement of C60 guest through the cavity of [9]CPP host should be experimentally observable owing to the relatively low energy barrier (

To design near-infrared (NIR) absorbing photosensitizing compounds, we theoretically elucidated the geometrical structures and electronic transition properties of four porphyrin-based and four phthalocyanine-based derivatives. The results show that fusion of a π-conjugated aromatic ring with the pyrrole rings of porphyrin can cause the larger red-shifts in the Q-bands than π-conjugated groups in the meso positions of porphyrin do. The extent of the red-shift of the absorption bands induced by the coordinated metal atom depends on the electrons occupied in their outer shell. The electron-donating groups also affect the absorption properties of porphyrins due to the σ → π bond formed between the donor groups and the porphyrin ring. Based on these calculated results, we found a phthalocyanine-based compound containing Ti metal that has an absorption wavelength of 977.5 nm and a molar extinction coefficient of 10 4 L/mol cm. Moreover, the intrinsic reasons for the significant absorption properties for the phthalocyanine-based compounds were revealed.

Two isostructural metal–organic polymers, namely {[M(bce)(bib)]·solv}n (M = Co(II) and solv = CH3OH·H2O for 1; M = Ni(II) and solv = 0.5CH3OH·0·25H2O for 2) (H2bce = 1,2-bis(4-carboxy-phenoxy)ethane and bib = 2,3-bis(4-pyridyl)butane), have been synthesized and characterized. The structures of the two compounds show 2D → 2D parallel interpenetrated frameworks with polyrotaxane and polycatenane character. The magnetic behaviors of 1 and 2 indicate antiferromagnetic interactions within paddle-wheel units. Furthermore, the compound 1 exhibits relative high N2 uptake adsorption capacity.

Geometry optimizations of the quinoline-based platinum (II) complexes (1-R, 2-R) and their related calculations on excited state energies, electronic absorption spectra and orbital populations have been carried out by the hybrid density functional theory (DFT) and its time-dependent approach (TD-DFT). The solvent effects on excitation energies are taken into account using the conductor-like polarizable continuum model (C-PCM). The red-shifted level of absorption bands, energy gaps between the singlet ground state (S1) and the first triplet excited state (T1) for each examined complex have been elaborated thoroughly as well. We find that the quinoline-8-thoil (ligand 2) induces much more significant red-shifted level than 8-hydroxyquinoline (ligand 1), and singlet-triplet splitting energy gaps of all examined complexes are bigger than threshold energy to yield singlet oxygen. It is revealed that the electronic red-shifted absorption bands originate from metal-to-ligand charge transfer (MLCT) transitions, and also shown that the quinoline-based Pt (II) complexes with strong donor groups could be considered as potential candidates for unearthing of novel photosensitizers in photodynamic therapy (PDT).

A self-assembled, (H2O)38 cluster stabilized by a mono-nuclear copper(II) complex 1 namely {[Cu(phen)2(CO3)]·7H2O} is characterized by X-ray diffraction studies. The adjacent (H2O)38 clusters connect together resulting in an infinite 2D water layer structure. The water morphology is stable at room temperature, but upon thermal decomposition, the water loss is irreversible.

A mono-nuclear copper (II) complex 1, formulated {[Cu(phen)2(CO3)]·7H2O} has been synthesized and characterized by X-ray diffraction studies, FTIR, and thermogravimetric (TG) analysis. However, there is a self-assembly structure of (H2O)38 cluster in this complex 1, and it is worth reporting. The adjacent (H2O)38 clusters connect together resulting in an infinite 2D water layer structure. The water morphology is stable at room temperature, but upon thermal decomposition, the water loss is irreversible. A mono-nuclear copper (II) complex 1, formulated {[Cu(phen)2(CO3)].7H2O} has been synthesized and characterized by X-ray diffraction studies, FTIR, and thermogravimetric (TG) analysis. However, there is a self-assembly structure of (H2O)38 water cluster in this complex 1, and it is worth reporting. The discrete (H2O)38 cluster connects together resulting in an infinite 2D water layer structure. The alternate arrangement of the complex 1 and the 2D water layer produce infinite through-channels along a axis direction, and the part moieties of complex 1 are located inside these channels. The water rings are stable at room temperature, and when thermally decomposes the water loss is irreversible.

The nanoscale host-guest interactions between [n]cycloparaphenylene ([n]CPP; n = 10, 8 and 9) nano-ring and fullerene C60 were explored theoretically. It is found that relatively small variations in the sizes of the [n]CPP host lead to very significant changes in encapsulation property toward the fullerene C60 guest. Expectedly, one stable inclusion-configuration of [10]CPP⊃C60 and one floating-configuration of [8]CPP⊃C60 are located on the potential surfaces of the two complexes, respectively. Unexpectedly, besides a floating-configuration (F-[9]CPP⊃C60), another stable inclusion-configuration (I-[9]CPP⊃C60) is also located on the potential surface of [9]CPP⊃C60 host-guest complex. Interaction energies and natural steric analysis show that these complexes are stabilized by balancing concave-convex π-π attractive and steric repulsive host-guest interactions. In contrast, the steric repulsive energy (Es) between host and guest of I-[9]CPP⊃C60 is as high as 233.12 kJ mol(-1), which is much larger than those in other complexes. The movements of C60 guest through the cavities of [n]CPP host (n = 10, 8 and 9) are simulated by calculating the energy profile, and the results interestingly reveal that the encapsulation of C60 by [10]CPP is in the manner of a single-potential well, by [8]CPP in the manner of a double-potential well, and by [9]CPP in the special manner of a three-potential well. We predict that the movement of C60 guest through the cavity of [9]CPP host should be experimentally observable owing to the relatively low energy barrier (50 kJ mol(-1), M06-2X/6-31G(d)). Charge population analysis shows that an obvious charge transfer between host and guest takes place during the formation of I-[9]CPP⊃C60, which is different from those during the formation of [8]CPP⊃C60, [10]CPP⊃C60 and F-[9]CPP⊃C60. Additionally, the host-guest interaction regions were detected and visualized in real space based on the electron density and reduced density gradient.

Two novel metal−organic frameworks (MOFs) of Co(II), {[Co(bpdc)(bpdap)]·1.5H2O}n (1) and [Co(bpdc)(Hpb)(H2O)]n (2) (bpdap = N,N‘-bis(2-pyridyl)-2,6-diaminopyridine, H2bpdc = biphenyl-4,4‘-dicarboxy...

A new V-shaped bis-monodentate ligand L (L = 2,3′-dipyridylamine) (1) has been designed and synthesized by alkylation reaction of pyridylamine. An investigation of the charge distributions of the coordination atoms and single-point energy calculations of four conformers of ligand L based on the geometry of conformers optimized by the DFT (density functional theory) method was carried out. The results show that the four conformers of ligand L take on two stable and two less stable configurations. Theory forecasts that two relatively stable configurations present in complexes as probable coordination motifs of the ligand, and that steric hindrance of pyridine nitrogen atoms in isomers will affect its coordination ability together with the electronic factor. This forecast has been demonstrated by the coordination chemistry of ligand L, that is, configuration (a) and (b) of the ligand occur in the following reported complexes, which combines with AgI or CuII through two coordination modes (bidentate bridging or a monodentate mode) resulting in coordination polymers {[Ag (L)2]NO3}n (2), [Cu2(L)2(maa)4]n (maa = methacrylic acid) (3), and the mononuclear molecule [Cu(L)4](ClO4)2·2CH3CH2OH (4). The ligand assumes different coordination modes in the three complexes because of different levels of steric hindrance of the pyridine nitrogen atoms in the conformers. Interestingly, polymers 2 and 3 assume a 1D helical structure and a linear framework, respectively, and 4 has a 2D supramolecular architecture induced from hydrogen bond interactions. In addition, the magnetic properties of 3 have been explored, which shows a strong antiferromagnetic interaction.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Two novel supramolecular complexes [Cu(bpapa)(dhbd)]·CH3OH (1) and [Cu(bpapa)(ma)]·ma (2) (bpapa=bis[6-(2-pyridylamino)pyrid-2-yl]amine, dhbd=2,3-dihydroxybutanedioate dianion, ma=α-methacrylate) were rationally designed, synthesized and characterized by single crystal X-ray diffraction, IR, electronic spectroscopy and thermogravimetric analyses. Complex 1 was the first oligo-α-pyridylamino complex based on hydroxypolycarboxylate and self-assembled into a 3D honeycomb configuration network with open channels and tubes containing 1D ladder-shaped double chains formed by hydrogen bonds and aromatic π-π stacking interactions. Complex 2 constructed a 2D supramolecular network extended by 1D chains from dimeric supramolecular synthon through noncovalent supramolecular interactions. In the two complexes, the chelating monohelical ligand adopted all-anti configuration. Density functional theory calculations were applied to 1 and 2.

A new ligand dpa (dpa=3,4′-dipyridylamine) (1) has been designed and synthesized, which reacted with AgNO3 and ZnCl2, respectively, resulting in two new complexes, [Ag(dpa)2]NO3 (2) and [ZnCl2(dpa)2] (3). The complexes have been characterized by thermogravimetric analysis, spectroscopic techniques, and single crystal X-ray diffraction. 2 is one-dimensional (1D) helical chain structure formed by hydrogen bonding interaction, and the helices are connected by the electrostatic interaction between Ag(I) ions and O atoms from NO 3 − , leading to a two-dimensional (2D) supramolecular structure. For 3, the mononuclear [ZnCl2(dpa)2] is almost a regular tetrahedral configuration, which generates a dimeric structure constructed through N–H⋯Cl hydrogen bonds and π–π interactions between pyridine rings. The adjacent dimeric units extend further into two-dimensional rippled network structure by two kinds of hydrogen bonds (N–H⋯Cl, C–H⋯Cl) in different directions. On the basis of experiment, both two complexes were calculated by DFT-B3LYP/LANL2DZ in gaussian 03.

Two novel supramolecular complexes, [Cu(bpapa)(mal)]·H2O·CH3OH (1) and {[Cu(bpapap)](Hmal)2}·2H2O (2) [bpapa=bis-[6-(2-pyridylamino)pyrid-2-yl]amine, bpapap=2,6-bis-[6-(pyrid-2-ylamino)pyrid-2-ylamino]-pyridine, mal=maleate dianion] were rationally designed and synthesized based on flexible multidentate ligands and copper(II) maleate. Complexes 1 and 2 were all characterized by elemental analysis, spectroscopic techniques, thermal analysis and single crystal X-ray diffraction analysis. Complex 1 is of an infinite 3-D supramolecular framework constructed by 2-D sheets to contain 1-D helical chains formed by intermolecular hydrogen bond interactions between the non-coordinated oxygen atoms from maleate and nitrogen atoms from amino groups of bpapa. Complex 2 also takes a 3-D supramolecular structure, which is built from 2-D rhombic sheets produced by sequential dimer units. Interestingly, three pairs of symmetrical hydrogen bonds generate these dimer units.

A novel one-dimensional organic–inorganic coordination polymer based on a dinuclear copper unit, formulated [Cu 2 (cro) 4 (bpp)]·H 2 O (Hcro=crotonic acid, bpp=1,3-bis(4-pyridyl)propane) ( 1 ) has been synthesized and characterized by X-ray crystallography, spectral, thermal, XRPD and magnetic methods. The structure of 1 is fabricated by self-assembly of integrated Cu 2 (cro) 4 ·2H 2 O with collapse of the two apical water molecules and flexible ligand bpp into a 1D zigzag-shaped chain. Interestingly, wavy channels are formed among every four adjacent chains, and the water-dimers are situated at the apex of the channels.

Two novel 1-D coordination polymers, {[Cu(Hhbd)(bpy)]·3H2O}n (1) and {[Cu(Hhbd)(phen)]·H2O·MeOH}n(2) [Hhbd = α-hydroxybutanedioicate dianion, bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline], were rationally designed and synthesized with an identical construction strategy, using Hhbd ligands as bridges and chelating aromatic ligands as terminal ligands. Interestingly, the chelating aromatic ligand and the –OH groups of the Hhbd ligand play an important role in the self-assembly of the polymeric coordination chain by providing potential supramolecular recognition sites for π–π aromatic stacking and hydrogen-bond interactions, resulting in the self-assembly of the molecular double chains to give a 3-D supramolecular framework with 1-D open channels. More significantly, in 1 the host framework encapsulates unprecedented centrosymmetric cyclic (H2O)8 clusters that have a chair conformation and are connected into 1-D arrays by supramolecular association along the 1-D open channels. In contrast, the channels of 2 contain lattice water and disordered methanol molecules. TGA and XRPD show that the host frameworks of 1 and 2 are stable when the guest solvent molecules are removed from the channels. Variable-temperature magnetic susceptibility measurements for both complexes indicate the presence of weak antiferromagnetic exchange interactions between adjacent copper(II) ions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Late stage coarsening (Ostwald ripening) phenomenon in a two-dimensional colloidal system has been investigated via in situ observation of clusters in a polystyrene colloidal film subjected to an external alternating electric field. In a regime with a growth exponent n ≈ 0.23 for the mean cluster gyration radius ( r g ), the gyration radius distribution broadens with time and scales as r d g F( r g 〈r g 〉 ) , the exponent is the fractal dimension of the aggregation system.

The aggregation of two-dimensional colloidal polystyrene microspheres induced by an external alternating electric field was studied by in situ microscopy. Direct observations of cluster creation and evolution revealed that the system aggregates by a nucleation-limited mechanism. The kinetics under different experimental conditions are investigated. In this nucleation-limited aggregation, the cluster growth can be expressed in time by a power law with an exponent of 1 3 .

Structure formation in a polystyrene particle suspension film, under the action of an external alternating electrical field perpendicular to the film, is systematically studied in experiments; the interaction force between particles, induced by the electrical field, is analyzed. Based on the experimental results, a phenomenological theoretical interpretation is suggested. A preliminary quantitative comparison between the theory and experiments shows agreement.

The aggregation of two-dimensional polystyrene particles, induced by an external alternating electric field, is experimentally studied by means of in-situ microscopy; specifically, the percolation behavior is addressed. The experimental results show that a percolation transition occurs approximately at the particle concentration ${\mathit{p}}_{\mathit{c}}$=0.42, which is less than the value predicted by the lattice percolation theory. The fractal dimensions of clusters are calculated and are in agreement with those predicted by the percolation theory.

The first-principles density functional theory (DFT) and its time-dependent approach (TD-DFT) are used to characterize the electronic structures and optical spectra properties of five chemically modified fullerenes. It is revealed that the metal fullerene derivatives possess not only stronger absorption bands in visible light regions than organically modified fullerene but also the large energy gaps (ΔE(S-T) > 0.98 eV) between the singlet ground state and the triplet state, which imply their significant aspect of potential candidates as a photosensitizer. We have found that a new metal-containing bisfullerene complexes (Pt(C(60) )(2) ), with the extended conjugated π-electrons, much degenerate orbitals and a uniform electrostatic potential surface, behave more pre-eminent photosensitizing properties than other examined fullerene derivatives.

We report the study of the random deposition process in polystyrene colloidal solution film. We analysed the morphology of the formed interface and measured the scaling exponents α and β, defining the interface width w(L, t) ≈ L α f(t/L α/β ) , where f(x) ≈ 1 for x ⪢ 1 and f(x) ≈ x β for x ⪡ 1, the values of which are 0.5 and 0.26, respectively. We also compared the result with the theoretical model describing the deposition process.

The electronic structures and dielectric properties of TiO2 –graphene composites are studied using pseudo-potential density functional theory. It is shown that interfacial charge transfer properties of graphene/ TiO2 are influenced by the atomic type on TiO2 surface. The interfacial interaction of graphene with Ti -terminated surface is so strong that it causes a buckling structural graphene, and the titanium atomic d electrons are transferred obviously from TiO2 to graphene. It is revealed that dielectric properties of the composites are greatly affected by both band structures and electronic transitions. Compared with bulk TiO2 , dielectric constants of TiO2 –graphene composites are significantly improved.

With a combined methodology of quantum chemistry and statistical mechanics, two Yb@C76 isomers are disclosed to possess novel fullerene structures which contain one pair of adjacent pentagons and are related by a single Stone–Wales transformation.