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We present a novel approach to second harmonic microscopy combining variable temperature and photon counting. This innovative method aims to generate Second Harmonic Generation (SHG) images by scanning the same area multiple times with short pixel dwell times and low excitation intensities, as illustrated by imaging the full extent of a single crystalline rod of (1,4-bis((4′-(iodoethynyl)phenyl) ethynyl) bicyclo[2.2.2]octane (BCO). Remarkably, this new technique records the change in SHG intensity that occurs along with the crystalline phase transition at 108 K, thereby showing great promise in exploring the intricate instabilities of rotator dynamics concealed within the phase diagrams of molecular machines. Notably, our findings reveal a sustained decrease in non-linear optical intensity as the temperature drops to 95 K, followed by a sharp increase in SHG intensity at approximately 108 K, in synchronicity with the phase transition reported earlier that involves an intricate set of concerted changes in rotor dynamics. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of redox-active, tetrathiafulvalene (TTF)-phosphine and ferrocene (FC)-phosphine complexes based on a hexanuclear rhenium chalcogenide cluster core that delivers three-dimensional pi-donor hybrid molecules. Cyclic voltammetry experiments demonstrate that these compounds can be reversely oxidized at rather low potentials allowing an easy access to the corresponding radical species.

A face-capped octahedral cluster with 25 metal-based valence electrons- specifically, [Re4Os2Se 8(CN)6](super 3-) is capable to participate in magnetic exchange coupling. The observed ferromagnetic coupling with appended Cu(super II) centers is weak as a result of the cluster spin being diluted over its sizeable core.

The ability of I...I van der Waals interactions to direct the self-assembly of slabs of the radical cation of ethylenedithio-1,2-dilodo-tetrathiafulvalene, EDT-TTF-I2, and polymeric lead iodide covalent anionic layers is demonstrated by the synthesis of single crystals of beta-(EDT-TTF-I2)(sub 2)(super .+)[(Pb(sub 5/6)square(sub 1/6)I2)(super 1/3)](sub 3). A complementary, commensurate pattern of association is revealed at the organic-inorganic interface.

Research has been conducted on the hexanuclear rhenium chalcohalide clusters. The solution chemistry of these clusters has been investigated in the effort to explore the redox chemistry of the electron-rich mineral molecular forms and their substitutional patterns.

A novel method of synthesizing related cage molecules and macrocyclophanes was developed through the use of the same technique for synthesizing TTF vinylogues. The design utilized bis(1,4-dithiafulvenes) as primary substrates. The intermediate underwent the same redox behavior as with 1,4-diathiafulvenes.

Tetrabutylammonium salts of the chalcogen-enriched heterosubstituted, hexanuclear molecular cluster dianions were yielded at room temperature in a reaction of (n-Bu4N)(Re6Q5Cl3(Cl6)) (Q = S, Se) with ((CH3)3Si)2E, (where E = O, S, Se, Te) reagents. Heterosubstituted hexanuclear molecular cluster dianions have been characterized with liquid secondary negative ion mass spectrometry and crystallographic data is presented. A decrease in thermalized average Re-Cl overlap clusters with increased cluster charge is discussed.

The syntheses and structural characterization of the octahedral Re6 cluster anions (Re6S5Cl9) and (Rb+)5(Re6S6Cl8(super 2-))(Re6S7Cl7(super -3)) as well as the molecular (Re6S4Cl10) and the neutral linear-chain polymer (Re6S5Cl8) are discussed. The synthesis is based on the preparation of salts, Rbn(Re6S(sub 4+n)Cl(sub 10-n)), where n = 1-3. The reductive-oxidative and crystallograpic properties of the complexes are discussed.

The results of an analysis of fully oxidized and moderately coupled dimers is reported. The synthesis of thiocyanato-functionalized cluster halide as a tetrabutylammonium salt is also reported. The molecular structure of ((Mes)4TTF)2(MoCl8(NCS)6) includes discrete organic dications interspersed between functionalized cluster dianions in a Cs-Cl type structure. There were smaller coordinating MoNC angles for the isothiocyanate ligands and the Mo6Cl8 cluster core than those of the tetrabutylammonium salt.

A study was done on the neutral molecular component site along the series of metallic organic-inorganic solvates. The series of single crystals composed of a monoanion which is a hexanuclear chalcohalide rhenium cluster and the neutral guest molecules are dimethylformamide. The compounds possess similar basic structural organization in which conducting organic cation radical slabs are sandwiched by inorganic cluster monoanion layers.

Four new mesitylene-anchored dithia- and tetrathiafulvenyl (DTF and TTF) pi-donors with threefold symmetry are synthesized and characterized by cyclic voltammetric, electrocyrstallization and X-ray methods. The studies show that Ph(DTF)3 oxidizes into an electroactive polymer while its methyl derivative does not. For the TTF derivatives, each redox unit behaves independently and cation radical salts can be grown electrochemically thereon. The empirical results are supported by molecular orbital calculations.

Double-sheet coordination polymer layers interspersed with H2O molecules characterize the two-dimensional Gd2(oxalato)(Cu 1,3-propylenebis oxamato)3(Cu H2O 5).20H2O structure. The oxalato bridges, which connect Gd(III) ions, form a parallel double-sheet honeycomb pattern featuring a puckered ladderlike Gd(Cu pba)-connected arrangement. Additionally, the zero-field magnetic susceptibility results show that the three-dimensional ordering of the compound takes place below 1.3 Kelvin. Low- and high-field magnetization analyses indicate that the magnetic interaction of the structure is relatively weak.

Nickel dithiolene complexes symmetrically appended with hydrogen-bond donor/acceptor functionalities such as imide, amide, or cyano/amide groups are synthesized by a straightforward method of wide applicability starting from one single precursor. Single-crystal X-ray structures reveal the occurrence of one type of ribbon common to all compounds that is based on a recurrent self-complimentary intermolecular hydrogen-bonded ring motif.

We have investigated the infrared spectra of the quarter-filled charge-ordered insulators δ-(EDTTTF- CONMe2)2X (X= AsF6, Br) along all three crystallographic directions in the temperature range from 300 to 10 K. DFT-assisted normal mode analysis of the neutral and ionic EDT-TTF-CONMe2 molecule allows us to assign the experimentally observed intramolecular modes and to obtain relevant information on the charge ordering and intramolecular interactions. From frequencies of chargesensitive vibrations we deduce that the charge-ordered state is already present at room temperature and does not change on cooling, in agreement with previous NMR measurements. The spectra taken along the stacking direction clearly show features of vibrational overtones excited due to the anharmonic electronic molecule potential caused by the large charge disproportionation between the molecular sites. The shift of certain vibrational modes indicates the onset of the structural transition below 200 K. [ABSTRACT FROM AUTHOR]

A series of two dimensional (2D) metals is shown to have one single [beta]-slab layered topology despite successive increases of the cluster anion negative charge. The BDT-TTP salts have provided a series of materials with strongly related but slightly different Fermi surfaces.

A unique hydrogen-bonding network is created between inorganic layers of the hybrid perovskites. Hydrogen bonding can provide a channel for stronger electron coupling between perovskites sheets, contributing to the reduction of band gap.

A perspective on the effort accomplished to direct intermolecular interactions in crystalline molecular conductors based on tetrathiafulvalene derivatives is provided. The focus is on the use of directional, electrostatic, normal and weak hydrogen bonds and halogen bonds.

PdCl2 and PtCl2 complexes of the redox active diphosphine P2 have been synthesized, and the palladium one is structurally characterized. It is found that the single crystal x-ray analysis on the resulting compound showed the formation of a dimeric complex salt, formulated as [(dppen)PdCl](sub 2)(OTf)(sub 2).

The deliberate design of a series of single crystals for conducting two-dimensional radical cation salts of o-bis(amide)-appended ethylenedithiotetrathiafulvalene, beta'-[EDT-TTF-(CONH2)2]2X (X = HSO(sub 4)(super -1), ClO(sub 4)(super -1), ReO(sub 4)(super -1)or AsF(sub 6)(super -1) and of their parent monocomponent solid EDT-TTF-(CONH2)2 is discussed. A recurrent, puckered ribbon constructed out of self-complementary, hydrogen-bonded amide...amide ring motifs is an important design element.

We report a facile desymmetrization of 1,4‐diethynylbicyclo[2.2.2]octane. One of the acetylene termini was protected by TMS and the desired product was purified by sublimation. It is stable but reactive, as shown by the synthesis of a complex pyridine‐terminated molecular rod containing both a bicyclo[1.1.1]pentane and a bicyclo[2.2.2]octane cage. Six crystal structures of key intermediates are presented. Facile desymmetrization of 1,4‐diethynylbicyclo[2.2.2]octane based on TMS protection of one of the acetylene termini followed by sublimation of the desired product is presented. The reactivity of this derivative was demonstrated in the synthesis of a complex pyridine‐terminated molecular rod containing both a bicyclo[1.1.1]pentane and a bicyclo[2.2.2]octane cage. [ABSTRACT FROM AUTHOR]

Electrocrystallization of the (S,S,S,S) enantiomer of tetramethyl-bis(ethylenedithio)-tetrathiafulvalene donor 1 in the presence of the dianionic hexanuclear rhenium (III) cluster [Re6S6Clg]2- affords a crystalline radical cation salt formulated as [(S)-1]2⋅Re6S6Cl8, in which the methyl substituents of the donors adopt an unprecedented all-axial conformation. A complex set of intermolecular TTF⋯TTF and cluster⋯TTF interactions sustain an original tridimensional architecture. [ABSTRACT FROM AUTHOR]

Variable-temperature (VT) crystal structures, VT 1H spin–lattice relaxation in static crystals, and DFT modelling of the rotational barriers of BCP rotators in crystalline arrays of a rod-like molecule containing two 1,3-bis(ethynyl)bicyclo[1.1.1]pentane (BCP) units demonstrate that a correlated gearing motion occurs in the limit of a weak coupling between two rotors in a pair. [ABSTRACT FROM AUTHOR]

We report on the structures of three dibromothiophene compounds (4, 5, and 12) and the analysis of the patterns of self-assembly in the solid state by C-- Br--Br--C halogen bonds of a selected set of 16 di- or poly-bromine-- (poly)thiophene monomers sorted according to the dimensionality of their halogen-bonded, extended frameworks thereby identifying syn- or anti-strings and layers. We conclude that in 1, 2, 9, and 10, the antiparallel orientation of successive C-- Br--Br--C halogen-bonded dibromothiophene units along extended anti-strings is linked to the occurrence of solid-state polymerization. [ABSTRACT FROM AUTHOR]

BOOK REVIEW Surfactants and Polymers in Drug Delivery. Drugs and the Pharmaceutical Sciences. Volume 122 by Malmsten, Martin

We report on the structures of three dibromothiophene compounds (4, 5, and 12) and the analysis of the patterns of self-assembly in the solid state by C-- Br--Br--C halogen bonds of a selected set of 16 di- or poly-bromine-- (poly)thiophene monomers sorted according to the dimensionality of their halogen-bonded, extended frameworks thereby identifying syn- or anti-strings and layers. We conclude that in 1, 2, 9, and 10, the antiparallel orientation of successive C-- Br--Br--C halogen-bonded dibromothiophene units along extended anti-strings is linked to the occurrence of solid-state polymerization. [ABSTRACT FROM AUTHOR]

We report on the synthesis and application of a 2 nm long, curved ditopic biscarboxylic ligand with a 1,4-bis(ethynyl)bicyclo[2.2.2]octane rotator core and an helical twist to the construction of an extended single-crystalline framework solid with paddlewheel hinges, [CuII]2[1,4-bis(carboxyphenyl ethynyl)bicyclo[2.2.2]octane]2(H2O)2 or [CuII]2(bbcbco)2(H2O)2. The interconnection of interpenetrated square lattices involves short rotor-rotor H ···H interactions (1.9 to 2.4 Å) such that the moving parts are expected to rub onto each other in the lattice in a Brownian rotational motion with a calculated rotational barrier of 3.7 kcal ·mol-1. Variable-temperature 1H spin-lattice relaxation ( T1) experiments carried out on a static crystalline sample did not provide however a value of this rotational barrier because the relaxation proved to be dominated by the coupling of the moving protons to the electronic spins of the CuII dimers. Remarkably, we reveal how the singlet-triplet spin dynamics of non-interacting CuII dimers is elegantly characterized by solid state NMR spectroscopic experiments yielding an exchange coupling constant, Jexp = -365 K = -254 cm-1, in good agreement with theoretical estimations and experimental data on related CuII dimer systems. [ABSTRACT FROM AUTHOR]

We report on a polymorph (2) of an amphidynamic crystal of molecular rods with two helical 1,4-bis(ethynyl)bicyclo[2.2.2]octane rotators where half of the rod-like molecules appear to be shifted with respect to their closest neighbours. This translation takes cogwheel-like pairs of rotators apart in the lattice in such a way that their motion becomes uncorrelated. This property is to be contrasted with the highly correlated motion found to govern the rotators in a recently-published polymorph 1 of the same material. As with polymorph 1, this motion is shown to take place independently of mutations in the handedness of the rotators and of the 'mutamer'-induced second harmonic generation. [ABSTRACT FROM AUTHOR]

Unconventional superconductivity typically occurs in materials in which a small change of a parameter such as bandwidth or doping leads to antiferromagnetic or Mott insulating phases. As such competing phases are approached, the properties of the superconductor often become increasingly exotic. For example, in organic superconductors and underdoped high-Tc cuprate superconductors a fluctuating superconducting state persists to temperatures significantly above Tc. By studying alloys of quasi-two-dimensional organic molecular metals in the κ-(BEDT-TTF)2X family, we reveal how the Nernst effect, a sensitive probe of superconducting phase fluctuations, evolves in the regime of extreme Mott criticality. We find strong evidence that, as the phase diagram is traversed through superconductivity towards the Mott state, the temperature scale for superconducting fluctuations increases dramatically, eventually approaching the temperature at which quasiparticles become identifiable at all. [ABSTRACT FROM AUTHOR]

The synthesis and full characterization (including X-ray structures) of two redox-active terpyridine–tetrathiafulvalene ligands namely (4′-amido-2,2′:6′,2′′-terpyridyl)-6,7-ethylenedithiotetrathiafulvalene (1) and 2-(4′-thioacetamide-2,2′:6′,2′′-terpyridyl)-3,6,7-tris(methylsulfanyl)-6,tetrathiafulvalene (2) are described. The binding properties of these multifunctional systems for various transition metal cations (Ni2+, Zn2+, Cd2+ and Fe2+) are analyzed in solution by cyclic voltammetry and UV-visible spectroscopy. In addition, a tetrahedral neutral zinc metal complex of ligand (2) formulated as (MeS)3-TTF-SCH2CONH-Tpy-ZnCl2·MeOH [complex (3)] and an octahedral nickel complex formulated as [{(MeS)3-TTF-SCH2CONH-Tpy}2Ni]·(ClO4)2·0.5(H2O) [complex (4)] are characterized in the solid state by X-ray diffraction. [ABSTRACT FROM AUTHOR]