Martin Putala

• PhD
• Head of Department at Comenius University Bratislava

We report a step‐efficient approach for the synthesis of unsymmetrically substituted naphtho[1,2‐g]chrysenes by tandem arylation of 2,2’‐diiodo‐1,1’‐binaphthyl with arylboronic acids, which proceeds through Suzuki coupling followed by intramolecular arylation by C−H activation. Substrate screening examining over 30 meta‐ and/or para‐substituted ary...

We report a Suzuki 2,2'-diarylation of the racemic 2,2'-diiodo-1,1'-binaphthyl which proceeds with deracemization via a pallada(IV)cyclic intermediate, induced by a simple chiral ligand─BINAP [2,2'-bis(diphenylphosphino)-1,1',-binaphthyl]. A systematic study of the reaction scope, using 45 arylboronic acids, reveals that the diarylated product is f...

We hereby report a successful design strategy for n-type semiconductor materials based on an analogy with efficient p-type semiconductors, by introducing electron-withdrawing groups while maintaining the symmetry of the molecules upon omitting one thiophene unit on each side of the oligoaryl core. Two series of dithienylnaphthalenes and quaterthiop...

A series of bithienyl-terminated surfactants with various alkyl chain lengths (from C8 to C13) and phosphono or chlorodimethylsilyl anchoring groups were synthesized by palladium-catalyzed hydrophosphonation, or platinum-catalyzed hydrosilylation as a key step. Surfactants were tested in pentacene or α-sexithiophene-based organic field-effect trans...

A series of ten 2-naphthyl and 2-anthrylbithiophene derivatives with electron acceptor groups were synthesised using the Negishi or Suzuki cross-coupling reaction as a key step. We present a comparison of theoretical and experimental values of the LUMO and gap energies of these derivatives and the effect of the various electron-withdrawing groups o...

Oligothiophenes and their functionalized derivatives have been shown to be a viable option for high-performance organic electronic devices. The functionalization of oligothiophene-based materials allows further tailoring of their properties for specific applications. We have synthesized a new thiophene-based molecule 1-[5′-(2-naphthyl)-2,2′-bithiop...

Herein we report the synthesis and characterization of C2-symmetric 2,6-bis(5′-alkyl-2,2′-bithiophen-5-yl)naphthalene derivatives with alkyl side chains of various length and shape, including even the less commonly examined cyclohexyl and cyclohexylalkyl groups. By investigation of how these side chains influence solubility, self-assembly and charg...

We devised and synthesized a series of electron-rich compounds featuring diphenylamine, carbazole or dibenzo[c,g]carbazole connected via phenylacetylene linkers to an aromatic central unit. The key synthetic step was a high yielding cross coupling reaction between halogenated (bi)naphthalene and organometallic reagents prepared in situ from termina...

Four catalytically relevant Pd(II) complexes involving N-heterocyclic carbenes (NHCs) and bidentate N- and P-donor ligands were synthesized and characterized. The structures and conformations of the complexes were elucidated on the basis of combination of dynamic NMR and DFT studies. Conformational studies in respect to hindered rotation around C-N...

The rotational barriers of four 2,2′-diaryl-1,1′-binaphthalenes have been determined on the basis of peak volume integration in variable-temperature 1H EXSY NMR spectra. They were consistent with those determined at higher temperatures by complete line shape analysis. DFT calculations at the B2-PLYP//B3LYP-D3/6-311++G(d,p) level provided relative e...

Nondestructive readout of light-driven molecular memory devices can be achieved by monitoring the alterations in the chiroptical properties of 1,1'-binaphthalene as a conformationally responsive chiral group. In our system, this signaling unit is connected via acrylamide linkers to the receiving diphenyldiazene fragment, which undergoes significant...

This work describes the thin-film fabrication technology and characterization of devices based on organic semiconductor 3,6-bis(5'-hexyl-2,2'-bithiophen-5-yl)phenanthrene (H2T36Phen). The surface morphology, optical, and electrical properties are investigated for thin organic films. It demonstrates that the solution-based depositions require differ...

Carbocyclic nucleoside analogs are highly biologically relevant compounds. A large variety of them already serve as drugs or are investigated with this aim in mind. This review analyses syntheses of major types of carbocyclic nucleoside derivatives including those of pharmacological interest. The emphasis of this review is on entecavir, a derivativ...

A series of new sterically hindered (R)-(2'-aryl-1,1'-binaphthalene-2-yl)phosphanes with ortho-substituted phenyls as aryl groups were prepared via Negishi monoarylation of enantiopure 2,2'-dibromo-1,1'-binaphthalene followed by lithiation and quenching with diphenylphosphanyl or dicyclohexylphosphanyl chloride. These ligands were applied to the st...

A series of ortho-substituted 2,20-aryl-1,10-binaphthalenes were prepared via Negishi arylation of 2,20- diiodo-1,10-binaphthalene in good to high yields (65–95%) as an equilibrium mixtures of up to three atropisomers (unlike,unlike, like,unlike, and like,like). Thermodynamic stability parameters of the atropi- somers were evaluated from VT NMR spe...

A series of new sterically hindered (R)-(2′-aryl-1,1′- binaphthalene-2-yl)phosphanes with ortho-substituted phenyls as aryl groups were prepared via Negishi monoarylation of enantiopure 2,2′-dibromo-1, 1′-binaphthalene followed by lithiation and quenching with diphenylphosphanyl or dicyclohexylphosphanyl chloride. These ligands were applied to the...

Organic field-effect transistors (OFETs) based on solution-processable organic semiconductors have experienced wide range of applications. Here we report fabrication, structure, and electrical properties of 2,6-bis(5'-hexyl-2,2'-bithiophen-5-yl)naphthalene (H2T26N) OFETs. The high-temperature tilt-casting has been used for preparation of giant grai...

2,2′-Diiodo-1,1′-binaphthalene undergoes a tandem Heck reaction with methyl acrylate to afford methyl 2-(7H-dibenzo[c,g]fluoren-7-ylidene)acetate. As a consequence, the target macrocyclic diazene with binaphthalene unit attached via acrylamide linker was prepared by the stepwise building of acrylamide at a binaphthalene moiety, including the Doebne...

Photophysical properties of new coumarin-3-carbaldehyde (dihydrodinaphtho[2,1-c:1',2'-e]azepin-N-yl)imines bearing dimethylamino and methoxy groups at position 7 of coumarin were investigated. Dimethylamino derivative exhibits different solvent polarity dependence of fluorescent characteristics for nonpolar, medium polar and highly polar solvents....

Several approaches were examined for the preparation of 1,1′-binaphthalene derivatives bearing sterically demanding ortho-substituted aryl at position 2′ which are suitable for further functionalization at position 2. Steric hindrance of ortho-substituted aryl groups was critical for the approach through BINOL monotriflate. Among variations of cros...

Semiconducting Organic Molecular Materials This feature article gives an overview of recent advances in development of high performance molecular organic semiconductors for field-effect transistors with emphasis on the structure of molecular materials and requirements for high-performance.

Enantiopure 10,10′-bi(naphtho[2,3-b]pyran) (5a) has been prepared from (R)-BINOL by using the attachment of 1,1-diphenylallyl alcohol to positions 3 and 3′ of the binaphthalenevia Heck coupling as a key step. The irradiation of 5a in solution with UV light at 313 nm caused photochemical opening of only one of the pyran rings, accompanied by minor c...

Bis-ortho- and bis-meta-phenylene homologues of BINOL-based N,N-dimethylphosphoramidites were prepared from the corresponding diols by treatment with hexamethyltriaminophosphane. Phosphoramidites derived from bulkier secondary amines were synthesized by 5-phenyl-1H-tetrazole-promoted amine exchange. All the phosphoramidites were obtained as single...

Axially chiral binaphthyl derivatives represent one of the most important groups of the artificial chiral-pool compounds. Their widespread applications lay stress upon their facile accessibility in enantiomerically pure state, as well as possibility of easy structural modifications. This article attempts to provide a representative review of all th...

Four 1,1′-binaphthalene based bis-urea derivatives bearing aryl groups at end-on nitrogen atoms IIIa–d were synthesized as potential sensor molecules. These receptors show characteristic UV-VIS spectral changes on complexation with anions and they exhibit selective recognition of F− over other halide anions. Interaction of a fluoride anion with ure...

Vibrational (VCD), electronic circular dichroism (ECD), and IR absorption spectra together with transparent spectral region optical rotation (OR) of two derivatives of bisphenylene 1,1'-binaphthyl-based phosphoramidites containing three stereogenic axes were measured and the results were compared with simulated data obtained by ab initio calculatio...

The use of monophos as a ligand in the palladium-catalyzed Suzuki diarylation of 2,2′-diiodo-1,1′-binaphthyl under optimized conditions followed a stereoconservative course. However, some chiral P ligands were found to be capable of inducing stereogenic information during this coupling, regardless of the configuration of the starting diiodide. Amon...

A synthetic approach is reported which allows independent introduction of alkynyl groups to positions 2,2′ and then to 6,6′ of binaphthyls. The approach is based on the high selectivity of the Stephens–Castro alkynylation of 6,6′-dibromo-2,2′-diiodo-1,1′-binaphthyl. The tetraalkynylated derivatives exhibit extended conjugation between groups at pos...

Suzuki diarylation of enantiopure 2,2′-diiodo-1,1′-binaphthyl catalyzed by triphenylphosphane palladium complex is accompanied by almost complete racemization of binaphthyl moiety (7% e.e.). Based on formerly proposed mechanism, secondary oxidative addition of Pd(II) to Pd(IV)-complex, competitive to transmetallation, is expected to be responsible...

The results of studies on the interactions of diazoalkanes with transition metal complexes are presented and the successive transformations of the diazoalkane complexes formed are traced. The reactions have been classified in terms of the proposed mechanism and the structure of the products. The principal structural parameters of the diazo-ligands...

An effective methodology has been developed for the synthesis of enantiopure 2,2'-dialkynylated 1,1'-binaphthalene derivatives. Enantiopure 2,2'-diiodo-1,1'-binaphthalene ( 10 ) provided 2,2'-diethynyl-1,1'-binaphthalene ( 16 ) in the Negishi alkynylation supported by microwave irradiation in a very good yield with conservation of stereochemical in...

The preparation of new bis-(10-alkyl-phenothiazin-3yl)-1,1'-binaphthalene derivatives 10,13, following a rational synthetic approach based on Suzuki or Negishi arylation of suitable precursors, is discussed. Positive results were obtained by Suzuki arylation of the (RS)-6,6'-dibromo-[ 1,1'-binaphthalene]-2,2'-dicarbonitrile ( 11) with 10-hexyl-3-(...

The Suzuki arylation of enantiopure 2,2'-diiodo-1,1'-binaphthalene affords the 2,2'-diarylated products in considerable yields (up to 52%), however, significantly racemized. The reversed-polarity approach, using novel enantiopure 1,1'-binaphthalene-2,2'-diyldiboronic acid, prepared either by resolution or by stereoconservative boronation, allowed,...

Negishi arylation and alkynylation of easily synthesized chiral 2,2'-diodo-1,1'-binaphthyl rapidly proceeds in refluxing THF utilizing controlled microwave irradiation, affording enantiopure 2,2'-diarylated 1,1'-binaphthyls in good to excellent yields.

The yield and the stereochemical outcome of methylations of 1,1′-binaphthyl-2,2′-dielectrophiles (ditriflate and diiodide) clearly depend on the reactivity of the organometallics used. It was found that only the Negishi reaction of a diiodide allows direct effective synthesis of non-racemic functionalised C2-symmetric 2,2′-dialkyl-1,1′-binaphthyls.

The first preparation of enantiomerically pure 1,1′-binaphthyl-2,2′-diboronic acid (by resolution) is reported. Optimization of the cross-coupling conditions was found to be crucial to achieve good yields in Suzuki arylation in approaches from both 2,2′-diiodide or 2,2′-diboronic acid (52–56%, with model p-tolyl reagents). Stereochemical results in...

The reaction of the title compounds and the transformations of the product, 3 were investigated with an emphasis on the stereochemistry. The primary interaction of the title compounds is feebly stereoselective. The diastereoisomers of product 3 exhibit free energies differing by ca. 16 kJ/mol; diastereoisomerization by helix inversion takes place d...

Palladium catalyzed Negishi, Suzuki and Stille cross-coupling reactions of enantiopure 2,2′-diiodo-1,1′-binaphthyl with the corresponding 1,1′-dimetalloferrocenes gave the C2-symmetric binaphthyl bridged ferrocene 1-1,1′-(1,1′-binaphthyl-2,2′-diyl)ferrocene (1). The latter was obtained by Stille coupling with the bis(trimethylstannyl) derivative bu...

The review deals with a unique type of substitution reactions of aromatic compounds in which retention of configuration is questionable, namely with substitutions in positions 2 and 2′ of C2-symmetric 2,2′-disubstituted 1.1′-binaphthyl derivatives. The stcreochemical aspect results from the fact that the nonbonding interaction of substituents in po...

The performed study on the cyanation of [1,1'-binaphthalene]-2,2'-diiodide and [1,1'-binaph- thalene]-2,2'-diyl ditriflate showed reactions with zinc cyanide catalyzed by palladium phosphane complex in DMF to be the most effective procedures with almost complete conservation of stereogenic information - affording corresponding highly enantiomerical...

Two theoretical methods have been tested to predict the structure of bridged ferrocene derivatives and their oxidized ferrocenium cations. Some of them have C2-symmetry and could be used as potential chiral catalysts. The bridge between cyclopentadienyl rings causes their deviation from coplanarity. The geometrical arrangement of catalytic center i...

The complexes Cp2Nb(H)(η1-NNCPhAr) (ArPh)) (1) or o-C6H4Br (2)) were found to undergo easy substitution of a hydride ligand for a halogen atom by the reaction of 1 with various alkylhalides with high yields of Cp2Nb(X)(η1-NNCPh2) (XCl (4), Br (5) or I (6), Cp2Nb(Br)(η1-NNC(Ph)-o-C6H4Br) (7) and5 were found to be formed in a halogen exchange react...

Diazoacetates N2CHCOOR (a: R = Et; b: R = t-Bu) readily react with Cp2NbH3 to give CP2NbH(η1-N2CHCOOR) (1) as the first identifiable product, characterized by means of 1H NMR spectroscope. Complex 1a converts stepwise into a unique binuclear nitrene niobocene complex [(C5H4-C(COOEt)=N-μ-N)C5H5)Nb]2 (2a). The latter is in fact a product of the Cp-li...

The reaction of Cp2MH3, where M  Nb or Ta, with N2CPh2, N2CPh(o-C6H4Br) and N2CHCOOEt was thoroughly studied. It was shown that the primary products of the reaction are the complexes Cp2M(H)(η1-N2CRR′) (2). The complexes 2 are readily oxidized by air to give polymeric (Cp2MO)n, N2CRR′ and RR′CN2CRR′.Interaction of an excess of N2CPh(o-C6H4Br) with...

Interaction of niobo- and tantalocene trihydrides (Cp2 MH3; M  Nb, Ta) with diphenyldiazomethane under mild conditions leads to monohydride complexes of a new type, Cp2 M(H) (η1-NNCPh2), where M  Nb I and Ta II. I and II have been characterized by a 1H NMR study, and I also by an X-ray single crystal diffraction study at 183 K (R = 0.029 for 1510...

The base-catalysed addition of thiourea to ferrocene analogues of chalcones is faster and more selective when the reaction mixture is sonicated than when merely heated. 4-Aryl-6-ferrocenyl- and 6-aryl-4-ferrocenyl-3,4-dihydropyrimidine-2(1 H )-tyhiones were isolated in 58-79% yields.