The method of Monte Carlo configuration interaction (MCCI) (Greer, J. Chem. Phys. 1995a, 103, 1821; Tong, Nolan, Cheng, and Greer, Comp. Phys. Comm. 2000, 142, 132) is applied to the calculation of multipole moments. We look at the ground and excited state dipole moments in carbon monoxide. We then consider the dipole of NO, the quadrupole of N2 and of BH. An octupole of methane is also calculated. We consider experimental geometries and also stretched bonds. We show that these nonvariational quantities may be found to relatively good accuracy when compared with full configuration interaction results, yet using only a small fraction of the full configuration interaction space. MCCI results in the aug-cc-pVDZ basis are seen to generally have reasonably good agreement with experiment. We also investigate the performance of MCCI when applied to ionisation energies and electron affinities of atoms in an aug-cc-pVQZ basis. We compare the MCCI results with full configuration interaction quantum Monte Carlo (Booth and Alavi, J. Chem. Phys. 2010, 132, 174104; Cleland, Booth, and Alavi, J. Chem. Phys. 2011, 134, 024112) and "exact" nonrelativistic results (Booth and Alavi, J. Chem. Phys. 2010, 132, 174104; Cleland, Booth, and Alavi, J. Chem. Phys. 2011, 134, 024112). We show that MCCI could be a useful alternative for the calculation of atomic ionisation energies however electron affinities appear much more challenging for MCCI. Due to the small magnitude of the electron affinities their percentage errors can be high, but with regards to absolute errors MCCI performs similarly for ionisation energies and electron affinities.

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The formation of hydrogels by the noncovalent assembly of organic molecules into nanoscale, cross-linked fibrous aggregates is highly topical and has been recently reviewed. [1] Hydrogels have wide-ranging potential applications in tissue engineering, [2,3] as vehicles for controlled drug delivery, [4,5] in the templated synthesis of nanoparticles and inorganic nanostructures, [6,7] in template polymerization, [8] and in pollutant capture and removal.[9] Small molecule hydrogelators frequently aggregate by hydrogen bonding, p-stacking, metal coordination, [8,10,11] and hydrophobic interactions to give often quite complex morphologies in a process that is closely related to crystallization. [12] In some cases it is thought that the solid-state structure of the gel fibers is the same as the structure of the crystalline gelator. [13,14] However, more commonly, either a different structure is adopted or the structure is unknown because the poorly crystalline nature of the gel or dried gel (xerogel) does not give powder X-ray diffraction (PXRD) patterns that are amenable to structure solution and refinement by Rietveld methods. The most common classes of gelators include nucleobases, saccharides, peptides, ureas, [15,16] and steroid derivatives.[12] Nucleobases [17,18] and related planar components, such as melamine [19,20] in particular, are interesting because of the multiple hydrogen-bonding interactions between complementary nucleobase pairs, suggesting that robust supramolecular gels might arise. In general however, nucleobases and other related heterocycles must be derivatized with long alkyl chains to give appropriate solubility properties and allow extensive hydrophobic interactions before they can act as gelators. Underivatized, rigid, planar molecules with such good hydrogen bonding functionality are commonly very insoluble as a result of the formation of very stable p-stacking and infinite hydrogen bonded chains in the solid state. Recent reports have shown, however, that sonication can induce gel formation. [21,22] Sonication is more commonly used to increase the dissolution rate of insoluble compounds. We reasoned that there may be a link between sonication-induced gelation and the partial solubilization of insoluble compounds, particularly for those compounds with strong hydrogen bonding functionality. Sonication-induced dissolution of small quantities of strongly hydrogen-bonding species may result in their rapid aggregation under nonequilibrium conditions and the deposition of a fibrous material without time for full crystallization to take place. Herein we present hydrogelation by a mixed system comprising two entirely rigid, insoluble, mutually complementary, planar multifunctional hydrogenbond donor/acceptors, namely melamine and uric acid (denoted M and U; Scheme 1), and we propose the likely structure of the gel from the results of crystal structure prediction calculations. [23][24][25] The melamine-uric acid (M-U) pair is related to the wellknown melamine-cyanuric acid rosette assemblies; [26,27]...

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Zwei Photonen sind besser als eines: Ein quadratisch‐planar koordinierter PtII‐Komplex mit Pyridinderivaten als Liganden (siehe Schema) geht bei Bestrahlung mit Licht von 600–740 nm einen zwei‐Photonen‐induzierten Ligandenaustausch ein. In Dichtefunktionalrechungen wurden die betreffenden elektronischen Übergänge identifiziert.

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