Antonio Frontera

University of the Balearic Islands | UIB · Department of Chemistry

Three homoleptic Hg(S 2 CNR 2) 2 , for R = ethyl (1), isobutyl (2), and cyclohexyl (3), compounds apparently exhibit a steric-dependent supramolecular association in their crystals. The small group in 1 allows for dimer formation via covalent Hg-S interactions through an eight-membered {-HgSCS} 2 ring as the dithiocarbamato ligands bridge centrosym...

H‐selenite anions (HSeO3−) form in the solid unprecedented anionic supramolecular chains wherein single units are assembled via alternating short Se···O and H···O contacts. Crystallographic analyses and computational studies (the quantum theory of “atoms‐in‐molecules”, QTAIM, and the noncovalent interaction plot, NCIPlot) consistently prove the att...

Two 1,3,4-oxadiazole-2-thione-N-Mannich derivatives, specifically 5-(4-chlorophenyl)-3-[(2-trifluoromethylphenylamino)methyl]-1,3,4-oxadiazole-2(3H)-thione (1) and 5-(4-chlorophenyl)-3-[(2,5-difluorophenylamino)methyl]-1,3,4-oxadiazole-2(3H)-thione (2), were synthesized and then characterized by elemental analysis and NMR (¹H and ¹³C) spectroscopy...

Volatile Organic Compounds (VOCs) are chemicals that vaporize at room temperature and exert short- or long-term adverse effects on human health and environment. In this study, Ag and Au nanoparticles...

Three new 1,3,4-oxadiazoles (1-3) have been synthesized. The crystal structure of two of them were solved by single crystal X-ray diffraction analysis and a detailed quantitative analysis of the weak non covalent interactions have been performed by using the DFT calculations. In both compounds it is observed the formation of recurrent H-bonded moti...

Two new metal(II) complexes [M(dmv)2(py)2]•3H2O {M = Ni (1), Zn (2)} were self-assembled from a metal(II) chloride salt, N,N’-dimethylvioluric acid (Hdmv), and pyridine (py). They were isolated as stable crystalline solids and characterized, including by single crystal X-ray diffraction. Structures 1 and 2 are composed of discrete [M(dmv)2(py)2] bl...

Computations at the PBE0-D3/def2-TZVP level of theory in conjunction with a Protein Data Bank (PDB) survey have provided first time evidence of favorable noncovalent interactions between ADP metavanadate (VO4) and ADP orthovanadate (VO5) and electron rich atoms. These involve a σ-hole present in the V atom and the lone pairs belonging to (i) protei...

In this study, the stability, directionality, and physical nature of Spodium bonds (SpBs, an attractive noncovalent force involving elements from group 12 and Lewis bases) between methylmercury (MeHg) and ethylmercury (EtHg) and amino acids (AAs) have been analyzed from both a structural (X-ray analysis) and theoretical (RI-MP2/def2-TZVP level of t...

In this study, a series of electron donor (-NH 2 ,-NMe 2 and-t Bu) and electron-withdrawing substituents (-F,-CN and-NO 2) were used to tune the nucleophilicity or electrophilicity of a series of square planar Ni 2+ , Pd 2+ and Pt 2+ malonate coordination complexes towards a pentafluoroiodoben-zene and a pyridine molecule. In addition, Bader's theo...

Novel nitronyl nitroxides, namely 2-(3-iodoethynylphenyl)-and 2-(4-iodoethynylphenyl)-4,4,5,5-tetramethyl-imidazoline-3-oxyl-1-oxides, were prepared by condensation of appropriate aldehydes with 2,3-dimethyl-2,3-dihydroxylamino butane followed by oxidative treatment with NaIO 4. Crystal and molecular structures of the obtained paramagnets were stud...

In this manuscript we report the synthesis and X-ray characterization of two cyanidoaurate telluronium salts, namely (3-fluorophenyl)(methyl)(phenyl)telluronium dicyanidoaurate [(3-F-Ph)(Me)(Ph)Te][Au(CN)2] (1) and methyldiphenyltelluronium dicyanidoaurate [(Me)(Ph)2Te][Au(CN)2] (2). In the solid state, the tellurium atom establishes three concurre...

Three cobalt complexes, namely [CoIII(HL¹)2(N3)2]ClO4 (1), [CoIII(L²)(HL²)(N3)]ClO4·1.5H2O (2), and [CoIII(L³)(HL³)(NCS)]2 [CoIICl2(NCS)2] (3), where HL¹ = 2-(3-(dimethylamino)propyliminomethyl)-6-methoxyphenol, HL² = 2-(2-(dimethylamino)ethyliminomethyl)-4,6-dichlorophenol, and HL³ = 2-(2-(dimethylamino)ethyliminomethyl)-6-methoxyphenol, as potent...

A doubly-interlocked [2]catenane – or Solomon link – undergoes a complex conformational change upon addition of sulfate in methanol. This transformation generates a single pocket where two SO42- anions bind...

Some literature reports have shown the existence of short Hg(II)···d8[M] (M = Pd, Pt) contacts between linear Hg(II) and square planar d8[M] complexes that have been defined as heterometallophilic interactions. Linear L–Hg(II)–L complexes exhibit a π‐hole or positive belt of electrostatic potential at the Hg atom, while late transition metals can s...

Combining computations and X-ray structure analysis we have demonstrated that [Pt(CN4)]2– can behave as a Lewis acid inside an enzyme’s cavity. The nature of a counterintuitive contact found between a catalytically active GLN residue belonging to a mitochondrial synthase and the Pt(II) center was investigated by combining Molecular Dynamics and Qua...

We report on a dendronized bis-urea macrocycle 1 self-assembling via a cooperative mechanism into two-dimensional (2D) nanosheets formed solely by alternated urea-urea hydrogen bonding interactions. The pure macrocycle self-assembles in bulk into one-dimensional liquid-crystalline columnar phases. In contrast, its self-assembly mode drastically cha...

We report on a dendronized bis‐urea macrocycle 1 self‐assembling via a cooperative mechanism into two‐dimensional (2D) nanosheets formed solely by alternated urea‐urea hydrogen bonding interactions. The pure macrocycle self‐assembles in bulk into one‐dimensional liquid‐crystalline columnar phases. In contrast, its self‐assembly mode drastically cha...

We report the crystal structure of the anhydrous form of Oxyma-B, a relevant racemization suppressor for peptide synthesis, solved by direct space methodologies from X-Ray Powder Diffraction Data. The structure...

In X-ray structures of the isomorphic mer-[IrX3(THT)(CNXyl)2] (X = Cl 1, Br 2; THT = tetrahydrothiophene; Xyl = 2,6-Me2C6H3-) complexes, we revealed short intermolecular contacts between the C-atom of an isocyanide methyl group and halide ligands of another molecule. Geometrical consideration of the X-ray data and analysis of appropriate DFT studie...

Homoleptic [L-I-L]⁺ iodine(I) complexes (where L is a R3R2R1N tertiary amine) were synthesized via the [L-Ag-L]⁺ → [L-I-L]⁺ cation exchange reaction. In solution, the amines form [R3R2R1N-Ag-NR1R2R3]⁺ silver(I) complexes, which crystallize out from solution as the meso-[L-Ag-L]+complexes, as characterized by X-ray crystallography. The subsequent [L...

The design of the secondary coordination sphere of metal complexes has emerged as a powerful synthetic strategy in their application/function in catalysis, molecular recognition, and crystal engineering. In contrast to traditional approaches, herein, the secondary coordination sphere of copper(II) complexes was designed by using chalcogen (sulfur)...

Reactions in water between the Cu2(µ-EGTA) chelate (EGTA = ethylene-bis(oxyethylene-imino)tetraacetate(4-) ion) and Hdap in molar ratios 1:1 and 1:2 yield only blue crystals of the ter-nary compound [Cu4(µ-EGTA)2(µ-H(N3)dap)2(H2O)2]·7H2O (1), which has been studied via single-crystal X-ray diffraction and various physical methods (thermal stability...

Progress with fluorescent flippers, small-molecule probes to image membrane tension in living systems, has been limited by the effort needed to synthesize the twisted push–pull mechanophore. Here, we move to a higher oxidation level to introduce a new design paradigm that allows the screening of flipper probes rapidly, at best in situ. Late-stage c...

Co-crystallization of the push-pull nitriles NCNR2 (R2 = Me2 1, C4H8 2, C5H10 3, C4H8O 4) with iodo-substituted perfluorobenzenes (1,4-diiodotetrafluorobenzene – 1,4-FIB and 1,3,5-triiodotrifluorobenzene – 1,3,5-FIB), gave cocrystals 1·1,3,5-FIB, 2·1,3,5-FIB, 3·½(1,4-FIB), 4·½(1,4-FIB), and 4·2(1,3,5-FIB), which were studied by single-crystal X-ray...

Reactions in water between the Cu2(µ-EGTA) chelate (EGTA = ethylene-bis(oxyethyleneimino)tetraacetate(4-) ion) and 2,6-diaminopurine (Hdap) in molar ratios 1:1 and 1:2 yield only blue crystals of the ternary compound [Cu4(μ-EGTA)2(μ-H(N3)dap)2(H2O)2]·7H2O (1) that has been studied by single crystal X-ray diffractometry, various physical methods (th...

Considering that Cu(tda) chelate (tda: dithioacetate) is a receptor for adenine and related 6-aminopurines, this study reports on the synthesis, molecular and crystal structures, thermal stability, spectral properties and DFT calculations related to [Cu(tda)(9heade)(H2O)]·2H2O (1) [9heade: N9-(2-hydroxyethyl)adenine]. Concerning the molecular recog...

The Cambridge Structural Database has been surveyed for crystals featuring Hg···S secondary-bonding interactions for mercury(II) compounds (excluding organomercury compounds). In all, 43 examples of crystals including intermolecular Hg···S contacts operating largely in isolation of other directional interactions were detected with the Hg···S contac...

The role of noncovalent interactions (spodium, halogen and hydrogen bonds) in the reaction of [Zn{NH=C(CCl3)NC(CCl3)=NH}2] with acetone, pyrazole, 4,4'-bipyridine and Cu(acetylacetonate)2 is reported. Depending on the reactants different types of organic, coordination and supramolecular compounds were isolated, and various types of noncovalent were...

Analyses of the Cambridge Structural Database and theoretical calculations (PBE0-D3/def2-TZVP level, atoms-in-molecules, natural bond orbital studies) prove the formation of net attractive noncovalent interactions between group 5 elements and electron-rich atoms (neutral or anionic). These bondings are markedly different from coordination bonds for...

Citation: Smirnov, A.S.; Kinzhalov, M.A.; Gomila, R.M.; Frontera, A.; Bokach, N.A.; Kukushkin, V.Y. Isocyanide π-Hole Interactions Supported by Aurophilic Forces. Abstract: Treatment of the [AuCl(tetrahydrothiophene)] complex with 4-chloro-2-iodo-1-isocyanobenzene furnished the gold(I) compound [AuCl(CNC 6 H 3-4-Cl-2-I)] (1). In the crystal structu...

Four series of Pt(II) tweezer compounds have been designed and synthesized in order to explore their ability to form supramolecular assemblies and influence upon their resulting luminescence. The compounds present the general chemical structure (diphos)Pt(N^N^N) where diphos is a diphosphane that differs on the flexibility and length chain (diphos...

Despite debate on intramolecular N/P interactions in peri-substituted naphthalene derivatives their coordination chemistry has not yet been reported. Herein, we describe bonding in and reactivity of dichloro(8-dimethylamino-1-naphthyl)phosphane towards pentacarbonyltungsten(0) reagents. A 1-aza-2-phospha-acenaphthene complex was obtained via the un...

Four manganese(III) complexes, [MnL1(H2O)2]ClO4$H2O (1), [MnL2(H2O)2]ClO4 (2), [MnL3(DMSO)(H2O)]ClO4 (3) and [MnL4(DMSO)(H2O)]ClO4 (4), where H2L1 = N,N′-bis(5-bromosalicylidene)-1,3-diaminopropane, H2L2 = 2,2-dimethyl-N,N-bis(3-methyloxysalicylidene)-1,3-diaminopropane, H2L3 = N,N′-bis(5-chlorosalicylidene)-2,2-dimethyl-1,3-diaminopropane and H2L4...

Treatment of the [AuCl(tetrahydrothiophene)] complex with 4-chloro-2-iodo-1-isocyanobenzene furnished the gold(I) compound [AuCl(CNC6H3-4-Cl-2-I)] (1). In the crystal structure of 1, the linear C–Au–Cl group is subject to the solid-state head-to-tail pairing which is determined by the aurophilic Au···Au and the rare π-holeCN···Cl interactions. Thes...

Cocrystallization of CuI with NCNMe2 in the presence of 1,4-diiodotetrafluorobenzene (1,4-FIB) and 1,4-dibromotetrafluorobenzene (1,4-FBrB) in MeCN gave cocrystals [Cu4I4(NCNMe2)4]·1,4-FIB, [Cu4I4(NCNMe2)2(NCMe)2]·1,4-FIB, and [Cu4I4(NCNMe2)4]·1,4-FBrB, whose solid-state structures were studied by X-ray diffraction. In these three cases, the perflu...

Three mixed-valence trinuclear cobalt(III)-cobalt(II)-cobalt(III) complexes, [CoII{(μ- L1)(μ-OAc)CoIII(OAc)}2]2.67H2O (1), [CoII{(μ-L1)(μ-OOCPh)CoIII(DMSO)0.8(OOCPh)0.2}2](ClO4)1.6 (2) and [CoII{(μ-L2)(μ- OOCPh)CoIII(DMSO)0.75(OOCPh)0.25}2](ClO4)1.5 (3), have been synthesized using two tetradentate N2O2 donor 'reduced Schiff base' ligands, H2L1 {1...

Considering Cu(tda) chelate is a receptor for adenine and related 6-aminopurines, now we report the synthesis, molecular and crystal structures, thermal stability, spectral properties and DFT calculations on the [Cu(tda)(9heade)(H2O)]•2H2O (1). N7 is found to be the preferred donor atom of 9heade, that can favor the cooperation of a Cu-N7(9heade) b...

Single crystal X-ray diffraction of iodate and bromate salts shows that the I and Br atoms in IO3- and BrO3- anions form short and linear O-I/Br···O contacts with the O atoms of nearby anions. Noncentrosymmetric systems are formed wherein anions are orderly aligned into supramolecular 1D and 2D networks. Theoretical evidences, namely the outcome of...

We report two distinct approaches to prepare unprecedented liquid-crystalline (LC) J-aggregates based on bis-core-dendronized naphthalene diimides (NDIs). The NDI 1 , with free imidic NH groups, spontanously self-assembles via hydrogen bonds...

Thallium compounds i.e. Tl+[S2P{OC6H3(2,5-(CH3)2)}2]- (1) and Tl+[S2P{OC6H3(3,5-(CH3)2)}2]- (2) stabilized by intra- and intermolecular triel bonds were isolated and characterized by FT-IR, NMR (31P, 1H and 13C) spectroscopy and SC-XRD analysis. The crystal structure of 1 and 2 belongs to monoclinic crystal system with space group C2/c and P21/n, r...

Two Na(I) coordination polymers, namely, {Na(BA)2(µ‑H2O)2}n{adp}n (1) and {[Na2(µ‑BA)(µ‑fum)(µ‑H2O)4](BA)}n (2) (where, BA = boric acid, adp = adipic acid, fum = fumarate), were prepared and characterized using elemental analysis, TGA, FT‑IR, and single‑crystal X‑ray diffraction techniques. Various unconventional supramolecular interactions, i.e.,...

[Cu2(μ-2-chlorobenzoato-O,O’)4Cl2].2(4-DMAPH) (1) and [Zn2(μ- 2-chlorobenzoato-O,O’)4(4-DMAP)2] (2) (4-DMAP=4-Dimeth- ylaminopyridine) were synthesized from CuCl2/Zn(NO)3)2 .6H2O, 2-chlorobenzoic acid and 4-dimethylaminopyridine in methanol under reflux. Compounds were comprehensively characterized by elemental analyses, conductance measurement, sp...

In this manuscript, we have examined the CSD (Cambridge Structural Database) to investigate the relative ability of Te and I (in practice, the heaviest chalcogen and halogen atoms) in di-and tri-iododiorganyltellurium(IV) derivatives to establish σ-hole interactions. The geometry around the Te(IV) in this type of compound is trigonal bipyramidal wh...

The synthesis of fluorescein propargyl diether (L) and two different dinuclear gold(I) derivatives containing a water-soluble phosphane [1,3,5-triaza-7-phosphatricyclo[3.3.1.13.7]decane (PTA) for complex 1 and 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane (DAPTA) for complex 2] has been successfully performed. All compounds display intrin...

The relevance of hydrogen-bonding, π-π stacking and aurophilic interactions in the solid-state of two new heterobimetallic (AuI-MnII) complexes is analyzed in this manuscript. They are discrete complexes of formulae [Mn(bipy)2(H2O){Au(CN)2}][Au(CN)2] and [Mn(dmbipy)2{Au(CN)2}]·H2O, (bipy = 2,2'-bipyridine and dmbipy = 5,5'-dimethyl-2,2'-bipyridine)...

Zn(II) (complex 1), Cd(II) (complex 2), and Hg(II) (complex 3) complexes have been synthesized using a triply protonated tptz (H3tptz3+) ligand and characterized mainly by single-crystal X-ray analysis. The general formula of all of the complexes is (H3tptz)3+·Cl-·[MCl4]2-·nH2O (where n = 1, 1.5, and 1.5 for complexes 1, 2, and 3, respectively). Th...

Pharmaceutical cocrystal landscape of ethenzamide has been addressed during the past years with the aim of improving its physicochemical properties, mainly solubility and dissolution rate. Herein four novel ethenzamide cocrystals...

Cationic imidazoliumyl(phosphonio)-phosphanides [LC-P-PR3]+ (1a-e+, LC = 4,5-dimethyl-1,3-diisopropylimidazolium-2-yl; R = alkyl, aryl) are obtained via the nucleophilic fragmentation of tetracationic tetraphosphetane [(LC-P)4][OTf]4 (2[OTf]4) with tertiary phosphanes. They act as [LC-P]+ transfer reagents in phospha-Wittig-type reactions, when con...

The chalcogen bond (ChB) is a noncovalent attraction between an electrophilic chalcogen atom and a nucleophilic (Nu) region in the same (intramolecular) or another (intermolecular) molecular entity: R-Ch⋯Nu (Ch = O, S, Se or Te; R = substituents; Nu = nucleophile). ChB is comparable to the hydrogen and halogen bonds both in terms of strengths and d...

In this study, we provide crystallographic (Protein Data Bank (PDB) inspection) and theoretical (RI-MP2/def2-TZVP//PBE0-D3/def2-SVP level of theory) evidence of the involvement of nucleobases in Regium−π bonds (RgBs). This noncovalent interaction involves an electrophilic site located on an element of group 11 (Cu, Ag, and Au) and an electron-rich...

The present study investigates the influence of noncovalent interactions in the design and structural control of crystal packing of pyrazoloquinoline derivative. Compound 3 was prepared in a two-step process in excellent yield. The reaction of 2,7-dichloroquinoline-3-carbaldehyde (1) and hydrazine monohydrate gave access to intermediate 2 which was...

In this study, the ability of CF3 groups to bind to the electron-rich side chains and backbone groups of proteins has been investigated by combining a Protein Data Bank (PDB) survey and ab initio quantum mechanics calculations. More precisely, an inspection of the PDB involving organic ligands containing a CF3 group and electron-rich atoms (A = N,...

In this manuscript we report the preparation of four new zinc complexes, [{(μ- CH3COO)ZnL1}2Zn]·2DMSO (1), [{(DMF)ZnL1(μ-CH3COO)ZnL1Zn(N3)}]·0.64DMSO·0.36EtOH (2) and [(μ-CH3COO)2Zn2L1]n (3) and [Zn2L2Cl2] (4) that were characterized by elemental and spectral analyses, where H2L1 is 1,3-propanediylbis(iminomethylene)bis(4-chlorophenol) and H2L2 is...

Organic crystals hold a significant importance in pharmaceuticals, biological systems and functional materials. In the present study, a tricyclic aromatic structure, tetrahydrocarbazole (THC), incorporating a nitrile functionality was synthesized via the Fischer indolization of 4-hydroxycyclohexanone with 4-hydrazinobenzonitrile hydrochloride in 70...

Understanding the molecular interactions that drive peptide folding is crucial to chemistry and biology. In this study, we analyzed the role of CO···CO tetrel bonding (TtB) interactions in the folding mechanism of three different peptides (ATSP, pDIQ, and p53), which exhibit a different propensity to fold in an α helix motif. To achieve this goal,...

Five new copper(I) complexes─composed of the paired dibenzohalolium and [CuL2]- (L = 1,2,4-oxadiazolate) counterions in which O,O-atoms of the anion are simultaneously linked to the halogen atom─were generated and isolated as the solid via the three-component reaction between [Cu(MeCN)4](BF4), sodium 1,2,4-oxadiazolates, and dibenzohalolium triflat...

In recent years Pd(II) and Pt(II) cases have been reported wherein metals in square planar complexes were used as nucleophilic partners to construct supramolecular assemblies with electrophilic molecules like σ-hole and π-hole donors. The formation of such assemblies is based on the nucleophilicity and accessibility of the dz2 orbital (in group-10...