Paula de Mendoza’s research while affiliated with Institute of Chemical Research of Catalonia and other places

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Publications (27)


Figure 1. (a) From left to right, the one-by-one construction of the aluminum organometallic complexes, with up to three Al atoms on the HATA molecule. The STM images were recorded at a 500 mV bias voltage and 200 pA constant tunneling current intensity. The chemical structure of the hexaazatrianthracene (HATA) molecule is inserted in the leftmost image in panel a. (b) Experimental STM zoomed-in images of Al x −HATA molecules (x = 0, 1, 2, and 3 from left to right), where the single Al coordinated adatoms can be observed (yellow arrows). (c) The corresponding simulated STM images using the optimized HATA surface structures presented in panel d, resulting from DFT calculations.
Figure 2. (a) The dI/dV tunneling spectra around the Au(111) surface Fermi level recorded by positioning the STM tip apex at the center of the molecule for each complex. For each bias voltage, those spectra were recorded using a lock-in amplifier with an 8 mV of voltage modulation. (b) The dI/dV differential conductance maps of the Al 1 − and Al 3 −HATA complexes recorded at −15 mV. Those conductance maps are presented contrast inverted because the −15 mV scanning bias voltage was set up slightly higher than the blue and dark-green Kondo resonance maxima in panel a to secure enough distance between the STM tip end apex and the HATA molecule. It fully reflects the state lying toward the low-energy region. 25 (c) DFT calculated projected densities of states (PDOS) for the three HATA complexes showing the magnetic character of the Al 1 − and Al 3 −HATA complexes. (d) The DFT calculated spin density maps of the Al 1 −HATA and Al 3 −HATA complexes. Al 2 −HATA is not presented because of no spin polarization in this case.
Figure 4. (a) The dI/dV spectrum exactly recorded at the center of the Al 3 −HATA molecular complex. (b) The differential conductance maps recorded at the energy of the two indicated different phonon channels. (c) The corresponding calculated vibrational modes at those energies. Each molecular vibration mode is collective motion, here, illustrated only with the corresponding core atoms. (d) A large series of spectra along the central line of the Al 3 −HATA complex. The low-energy phonon peak can be followed along from −0.7 to 0.7 nm relative to the center of the molecule (blue painted). The high-energy ones can be followed from −0.4 to 0.4 nm (purple).
Doublet-Singlet-Doublet Transition in a Single Organic Molecule Magnet On-Surface Constructed with up to 3 Aluminum Atoms
  • Article
  • Full-text available

September 2021

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145 Reads

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6 Citations

Nano Letters

We-Hyo Soe

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Paula de Mendoza

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[...]

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Christian Joachim

Starting from a long aza-starphene neutral and nonmagnetic organic molecule, a single-molecule magnet is on-surface constructed using up to 3 light nonmagnetic aluminum (Al) atoms. Seldom observed in solution with transition-metal atoms and going from 1 to 3 Al coordinated atoms, the doublet-singlet-doublet transition is easily on-surface accessible using the scanning tunneling microscope single-atom and single-molecule manipulations on a gold(111) surface. With 3 coordinated Al atoms, the lateral vibration modes of the Al3-aza-starphene molecule magnet are largely frozen. Using the Kondo states, this opens the observation of the in-phase Al vertical atom vibrations and out-of-phase central phenyl vibrations.

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Long Starphene Single Molecule NOR Boolean Logic Gate

April 2018

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46 Reads

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17 Citations

Surface Science

Using a low temperature scanning tunneling microscope (LT-UHV-STM), local electronic tunneling spectroscopy and differential conductance mapping are performed to investigate how by extending one phenyl more each branch of the conjugated board of a trinaphthylene starphene molecule, the corresponding longer trianthracene starphene new molecule is functioning like a NOR Boolean logic gate according to a Quantum Hamiltonian Computing (QHC) design. Here the STM tip is used to manipulate single Au atoms one at a time for contacting a trianthracene molecule. Each Au atom is acting like a classical digital input on the molecule encoding for a logical “0'' when the atom is not interacting with the trianthracene input branch and for a logical “1'' when interacting. The inputs are converted in quantum information inside the trianthracene molecule and the logical output status available on the output branch. QHC is demonstrated to be robust since quantum information transfer can be used on the long range along the trianthracene for the NOR logic gate to function properly as compared to the shorter trinaphthylene molecule.



Figure 1. (left) LDI-mass spectrum of crushed fullerene C 60 H 24 (5). (right) Theoretical and experimental isotopic pattern for C 60 H 24 (5). 
Figure 2. (a) (top) MALDI-mass spectrum of 5 at the threshold of ion formation using DHB as the matrix. (bottom) MALDI-mass spectrum of 5 at 129 μJ using DHB as the matrix. (b) (top) LDI + mass spectrum of C 60 fullerene at a laser power of 106 μJ. (center) LDI + mass spectrum of C 60 fullerene at a laser power of 115 μJ. (bottom) LDI + mass spectrum of 5 at a laser power of 126 μJ. 
Scheme 3. (a) Laser-induced formation of C 60 fullerene from 3 and 5. (b) Schlegel projections of 3 and 5 onto C 60 . 
Scheme 5. Synthesis tristriflate 10 from anti-4b and X-ray crystal structure of 8. 
Synthesis of a Crushed Fullerene C 60 H 24 through Sixfold Palladium-Catalyzed Arylation

May 2016

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108 Reads

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8 Citations

The synthesis of a new C3v-symmetric crushed fullerene C60H24 (5) has been accomplished in three steps from truxene through sixfold palladium-catalyzed intramolecular arylation of a syn-trialkylated truxene precursor. Laser irradiation of 5 induces cyclodehydrogenation processes that result in the formation of C60, as detected by LDI-MS.


Contacting a Conjugated Molecule with a Surface Dangling Bond Dimer on a Ge(001):H Surface Allows Imaging of the Hidden Ground Electronic State.

October 2013

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126 Reads

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33 Citations

ACS Nano

Fabrication of single-molecule logic devices requires controlled manipulation of molecular states with atomic-scale precision. Tuning molecule-substrate coupling is achieved here by the reversible attachment of a prototypical planar conjugated organic molecule to dangling bonds on the surface of a hydrogenated semiconductor. We show that the ground electronic state resonance of a Y-shaped polyaromatic molecule physisorbed on a defect-free area of a fully hydrogenated surface cannot be observed by scanning tunneling microscopy (STM) measurements because it is decoupled from the Ge bulk states by the hydrogen-passivated surface. The state can only be accessed by STM if the molecule is contacted with the substrate by a dangling bond dimer. The reversibility of the attachment processes will be advantageous in the construction of surface atomic-scale circuits composed of single molecule devices interconnected by the surface dangling bond wires.



SPM Imaging of Trinaphthylene Molecular States on a Hydrogen Passivated Ge(001) Surface

January 2013

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20 Reads

We report on studies concerning individual trinaphthylene molecules (Y molecules) deposited and anchored on the hydrogenated Ge(001):H surface. The characterization of single Y molecules has been performed by means of cryogenic temperature STM imaging using conventional STM tungsten tips and tuning fork-based sensors. In the latter case, a qPlus sensor facilitated simultaneous STM and NC-AFM measurements and thus molecular states were probed by both tunneling current and atomic forces concurrently. We show that the molecules are physisorbed, thus weakly interacting with the substrate. Contrary to the measurements on hydrogenated silicon, for planar aromatic molecules on the hydrogenated germanium, both empty and filled molecular states could be probed by STM.



Synthesis of fluoranthenes by hydroarylation of alkynes catalyzed by gold(I) or gallium trichloride

November 2011

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98 Reads

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40 Citations

Beilstein Journal of Organic Chemistry

Electrophilic gold(I) catalyst 6 competes with GaCl(3) as the catalyst of choice in the synthesis of fluoranthenes by intramolecular hydroarylation of alkynes. The potential of this catalyst for the preparation of polyarenes is illustrated by a synthesis of two functionalized decacyclenes in a one-pot transformation in which three C-C bonds are formed with high efficiency.


Citations (20)


... However, low operating temperature devices and related algorithms now are insufficient to support these applications. The research of SMM-based molecular spintronic devices is in the primary stage, which is challenging but meaningful for further investigation through the synergy between theoreticians, experimental physicists and chemists, and material scientists [133,134]. ...

Reference:

Approaching the uniaxiality of magnetic anisotropy in single-molecule magnets
Doublet-Singlet-Doublet Transition in a Single Organic Molecule Magnet On-Surface Constructed with up to 3 Aluminum Atoms

Nano Letters

... In 2020 [24], Soe et al introduced a novel tetrabenzophenazine molecule that effectively operated as a XORlike Boolean logic gate. Later in 2021 [25], the same group developed a digital full adder (3-input and 2-output) circuit using an aza-starphene molecule, implemented on a Au(111) surface. In 2021, Croshaw et al [22] examined the formation of continuous dangling bond (DB) wire structures on the hydrogen-terminated silicon (100)−2 × 1 surface. ...

A Single-Molecule Digital Full Adder
  • Citing Article
  • August 2021

The Journal of Physical Chemistry Letters

... Key to the synthesis of the PAH monkey saddle is the realization of a threefold bromo-substitution at the aromatic benzene rings in the cove regions of truxene at the 4-,9-, and 14 positions. [12] To overcome any possible solubility issues, we synthesized truxene 1 with hexyloxy chains and brominated it with NBS in DMF, which selectively occurred para to the alkoxy chains in the cove regions at 4,9,14-positions of the truxene. Tribromotruxene 2 was isolated in 32 % yield besides tribromotruxene 3, where one bromination occurred ortho to the alkoxy-chains (Scheme 1). ...

Synthesis of a Crushed Fullerene C 60 H 24 through Sixfold Palladium-Catalyzed Arylation

... It undergoes a first-order transition from a fluid phase to a solid phase with face-centered cubic packing [15,16]. More complicated shapes such as cubes, rhombohedra [17], or in general three-dimensional regular polyhedra or corner-rounded polyhedra [18][19][20] have been studied as more realistic models for experimental selfassembling systems [21][22][23], applications to drug delivery where shape of the carrier may decide its effectiveness [24], biological material like immunoglobin [25], molecular logic gates [26][27][28], etc. Being able to predict the macroscopic material behavior from knowing its constituent building blocks would help to engineer the synthesis of materials with prescribed properties [29,30]. ...

Contacting a Conjugated Molecule with a Surface Dangling Bond Dimer on a Ge(001):H Surface Allows Imaging of the Hidden Ground Electronic State.
  • Citing Article
  • October 2013

ACS Nano

... In a second step, controlled annealings from 200°C to 275°C initiated two successive cyclodehydrogenation steps with the formation of 3 new carbon-carbon bonds. A second conformer was also stable enough during the annealing step to give another compound in similar yield, the benzodibenzo [7,8,9,10]naphthaceno[2,1-h] phenanthro[9,10-p]hexaphene. The formation of this morehindered species stresses the importance of strong moleculesurface interactions during the cyclodehydrogenations steps of these large polyaromatic hydrocarbons. ...

STM and AFM high resolution intramolecular imaging of a single decastarphene molecule
  • Citing Article
  • August 2011

Chemical Physics Letters

... [75] Excellent reviews for the CÀ H bond functionalization with the activation of C sp À H, C sp 2 À H and C sp 3 À H under Au(I)-and Au(III)-catalysis have been documented. [76][77][78][79][80][81][82][83][84][85] However, the focus of this review is regioselective CÀ H functionalization reactions catalyzed by gold(I)-as well as gold(III)-complexes and the main contributions in this field. To develop an understanding of selectivity of such processes, mechanistic insights are provided at appropriate places. ...

ChemInform Abstract: Synthesis of Arenes and Heteroarenes by Hydroarylation Reactions Catalyzed by Electrophilic Metal Complexes
  • Citing Article
  • September 2010

ChemInform

... occurs when 2D materials are placed on a substrate, such as when they are epitaxially grown upon a metallic surface. [11,12] For example, it has been shown that molecules can become trapped within nanopores of hexagonal boron nitride grown on Ru (0001) because of dipolar interactions; [13,14] similar results have also been observed for nanopores on the surface of bulk SiC. [15] Physisorption of a molecule to a surface (i.e., van der Waals bonding) is often not strong enough to fix the molecule's position at room temperature, particularly on the surface of bulk metal crystals. ...

Templated growth of an ordered array of organic bidimensional mesopores

... The broadening of the bands and their batochromic shift are typical of porphyrins in polymerized state if the porphyrin cycle structure is preserved [24,38]. The changes in the ratio of the intensities of the Q-band αand β components can be caused by the changes in the energy of the central metal ion bond with the macrocycle [39], which results from the formation of additional coordination bonds between the zinc ion and the oxygen-containing fragments of the film [40] and out-of-plane macrocycle deformations in solid phase [41,42]. ...

Surface assembly of porphyrin nanorods with one-dimensional zinc-oxygen spinal cords

CrystEngComm

... of the channel, and the drain and source to have a greater influence, resulting in lower voltage and increased leakage. Therefore, digital circuit designers should consider adopting new technologies that overcome the challenges in COMS [1][2][3][4]. In chemistry, a dangling bond refers to an incomplete charge within an atom, and an atom with a dangling bond is called an immobile free radical. ...

Demonstration of a NOR logic gate using a single molecule and two surface gold atoms to encode the logical input

Physical review. B, Condensed matter