Michał J. Białek

Naphthalene-based linkers for metal phosphonates: synthesis, structure, and interesting conformational flexibility influence on final lanthanum hybrids

Two diphosphonic acids based on naphthalene scaffold, namely naphthalene-1,4-diphosphonic acid, C10H6(PO3H2)2 [1, H4NDP(1,4)] and 1-(phosphono)naphthalene-4-(methylphosphonic) acid, C10H6(PO3H2)(CH2PO3H2) [2, H4NDP(1,4C)] were obtained. Their supramolecular self-assembly were studied as well as solvent effect for the second one (2a, 2b). These potential building blocks in coordination polymer chemistry were engaged with a La3+ ion in a room temperature reaction to produce new single crystalline metal phosphonates: (I) [La{C10H6(PO3H)2}{C10H6(PO3H)(PO3H2)}(H2O)2]n·nH2O (3), a 2D coordination polymer with the I1O1 structure and {42.6}2{44.64.82} topology of the layer, and (II) [La{C10H6(PO3H1.5)(CH2PO3H)}2(H2O)7]·2H2O (4), a discrete complex. These drastic differences in hybrid material structures can be explained by ligand structures analysis including their conformational flexibility.

Beyond Single-Wavelength SHG Measurements: Spectrally-Resolved SHG Studies of Tetraphosphonate Ester Coordination Polymers

Powder second-harmonic generation (SHG) efficiencies are usually measured at single wavelengths. In the present work, we provide a proof of concept of spectrally resolved powder SHG measured for a newly obtained series of three non-centrosymmetric coordination polymers (CPs). CPs are constructed from tetrahedral linker-tetraphenylmethane-based tetraphosphonate octaethyl ester and cobalt(II) ions of mixed, octahedral (Oh), and tetrahedral (Td), geometries and different sets of donors (CoO6 vs CoX3O). Isostructurality of the obtained materials allowed for the determination of anion-dependent tunability of SHG optical spectra and their relationship with solid-state absorption spectra.

Oxidation and Oxygenation of Carbonyl Ruthenium(II) Azuliporphyrin.

Chemical oxidation and oxygenation of carbonyl ruthenium(II) azuliporphyrin [Ru(TPAP)(CO)] were explored. [Ru(TPAP)(CO)] reacts with dioxygen giving carbonyl ruthenium(II) 21-oxyazuliporphyrin [Ru(TPAP-O)(CO)] revealing the activation the Ru-C bond inside azuliporphyrin coordination cavity. Solution and X-ray structural studies confirmed the tendency of [Ru(TPAP-O)(CO)] to form dimeric [Ru(TPAP-O)(CO)]2. The dimer adopts a head-to-tail structure with the azulenolate groups forming bridges from one macrocycle to the ruthenium(II) in the adjacent unit. One-electron oxidation of [Ru(TPAP)(CO)] gives the first π-cation radical of metallocarbaporphyrinoid-[Ru(TPAP)(CO)](+•)-with extraordinary participation of the azulene unit in the spin delocalization. The most characteristic (1)H NMR features of the radical are large, sign-alternating isotropic shifts of resonances assigned to meso-aryl, azulene, and pyrrolic hydrogen atoms. The spin distribution determined by density functional theory confirmed the π-cation radical electronic structure reproducing the diagnostic spectroscopic features including π-delocalization at meso-aryl resonances and very characteristic sign alternation of contact shifts for an azulene moiety.

Incorporation of a Phenanthrene Subunit into a Sapphyrin Framework: Synthesis of Expanded Aceneporphyrinoids.

32-Hetero-5,6-dimethoxyphenanthrisapphyrins-macrocycles that link structural features of polycylic aromatic hydrocarbons and expanded porphyrins-were obtained in a straightforward [3+1] condensation reaction of dimethoxyphenanthritripyrrane and 2,5-bis(arylhydroxymethyl)heterocyclopentadienes. The highly folded conformation of formally 4 n π-electron macrocycles causes them to manifest only limited macrocyclic π conjugation as explored by means of NMR spectroscopic and X-ray structural analyses, and supported by DFT calculations. Although protonation does not change their π-conjugation characteristics, the cleavage of ether groups at the phenanthrenylene moiety yields nonaromatic 32-hetero-5,6-dioxophenanthrisapphyrins.

Carbocations Confined in a Thiatriazuliporphyrin Frame

In the search for tricarbaporphyrinoids, a three-component acid-catalyzed condensation of azulene, 2,5-bis[(p-tolyl)hydroxymethyl]thiophene, and an aryl aldehyde has been elaborated, affording the appropriate thiatriazuliporphyrinogens. The subsequent oxidation yielded a rare example of a macrocyclic organic tetracation, which can be readily and reversibly converted into macrocyclic tri- and dicarbocations by addition of one or two hydroxides bound at the meso position(s). Further insight into the influence of carbocation formation on the geometry, electronic structure, and magnetic manifestation in (1) H NMR spectroscopy has been obtained by using density functional theory calculations. The charge distribution was evaluated by mapping electron density surfaces with electrostatic potential (ESP).

A Parallel-Displaced Directly Linked 21-Carba-23-Thiaporphyrin Dimer Incorporating a Dihydrofulvalene Motif.

In the search of porphyrin arrays with a unique geometry, the efficient synthesis of a directly linked 21-carba-23-thiaporphyrin dimer with the distinctive dihydrofulvalene bridging motif has been developed. This compound acquires an uncommon parallel-displaced arrangement of two carbaporphyrin planes. The dimer undergoes an acid-triggered cleavage to create of the asymmetric carbathiaporphyrin-carbathiachlorin dyad or 2,3-dihalo-21-carba-23-thiachlorin depending on choice of acid. A formation of a reactive carbocation intermediate is postulated to account for mechanism of cleavage.

Aromaticity control via modifications of a macrocyclic frame: 5,6-dimethoxyphenanthriporphyrin and 5,6-dioxophenanthriporphyrin

The incorporation of a 9,10-dimethoxyphenanthrene moiety into a porphyrin framework results in the formation of a hybrid macrocycle – 5,6-dimethoxyphenanthriporphyrin 1, fusing the structural features of polycyclic aromatic hydrocarbons and porphyrins. Simple transformations of antiaromatic 1 led to two macrocycles incorporating phenanthrene and phenanthrenequinone units: isophenanthriporphyrin and 5,6-dioxophenanthriporphyrin. The reversible protonation of 1 at the central meso-carbon atom stabilizes its constitutional isomer, i.e. the Cs-symmetric isophenanthriporphyrin in its dicationic form 1-A-H22+. The addition of an acid to nonaromatic 5,6-dioxophenanthriporphyrin 2 yielded the aromatic tricationic form protonated at the carbonyl oxygen atoms. In the presence of tetrafluoroboric acid, etherate, 2 underwent borylation at carbonyl oxygen atoms forming the aromatic BF2-derivative.

Incorporation of a p-Phenylene Unit into the Azuliporphyrinogens Frame-Oxidation and Ruthenium Cluster Coordination

A porphyrinogen macrocycle incorporating two azulenes, phenylene and thiophene into the framework, joined by four C(sp3 ) atoms has been obtained as a mixture of six isomers. They were successfully separated and characterized spectroscopically. The identity of two of them was confirmed by X-ray crystallography. One isomer was tested in reaction with [Ru3 (CO)12 ] yielding exclusively π-complex with two clusters attached to azulenes. The partial oxidation of porphyrinogens yielded dication with two unmodified meso bridges. The stepwise oxidation followed by reaction with water as nucleophile afforded the dicationic species with two hydroxyl groups and a trication with one OH group. The hydroxy-dication can be reversibly transformed into hydroxy-trication by addition of HBF4 etherate.