Quantum Mechanical Investigations of Fullerene, Photoactive and Organometalic Molecules, Complexes, Supramolecules, Supermolecules and Design of Basic Elements of Digital and Postdigital Molecular Computing Devices

Summary of recent and current research at the Theoretical Molecular Electronics Research Group, Institute of Theoretical Physics and Astronomy, Vilnius, Lithuania, headed by Dr. Arvydas Tamulis

A. Tamulis^{*, a}, J. Tamuliene^{a}, M. L. Balevicius^{b}, V. Tamulis^{a}, Z. Rinkevicius^{c}

^{a}Institute of Theoretical Physics and Astronomy, A. Gostauto 12, 2600 Vilnius, Lithuania ^{b}Faculty of Physics, Vilnius University, Sauletekio al. 9, III rumai, 2054 Vilnius, Lithuania ^{c}Faculty of Fundamental Sciences, Kaunas Technology University, Studentu 50, Kaunas 3001, Lithuania

Quantum mechanical investigations of the stability of empty fullerene C_{20+2n} (n= 0, 2, 3, ..., 16) molecule isomers with the highest symmetry and the corresponding endohedral fullerene cages with twenty eight encapsulated atoms: even valence - Be, C, O, Mg, Si, S, Zn, Ge, Se, Cd, Sn, Te, Hg, Pb and odd valence - H, N, F, Al, P, Cl, Ga, As, Br, In, Sb, Tl, Bi were performed using the point set group theory in the framework of semiempirical MOPAC-PM3 method [1].

Taking into account 120 single excited configurations, calculations of singlet state bands of two fullerene C_{60} molecules in softer region are in good agreement with experimental values of absorption spectrum of C_{60} clusters in water solution or in the Langmuir-Blodgett films. The CNDO/S-CI calculation results show three new additional bands in the regions 342.90-364.46 nm, 427.28-437.08 nm and 481.58-495.88 nm [6]. Quantum chemical investigations of a charge transfer singlet state band of the proposed system consisting of two C_{60} molecules and two small charges are performed in the framework of CNDO/S-CI method taking into account 60 single excited configurations. Results of these calculations show the existence of a charge transfer band in this system of two C_{60} molecules [6].

The quantum mechanical investigations of fullerene C_{24}, C_{26}, C_{28} molecule conformers are performed in the framework of point set group theory and semiempirical PM3 configuration interaction, MNDO, AM1 and ab initio Hartree-Fock (HF) methods. The main criterion of stability of calculated fullerene molecules we state the lowest total energy of various isomers and conformers that appears due to the Jahn-Teller distortion. The most stable occurs C_{24} D_{6} symmetry conformation with term ^{1}A_{1} and open shell C_{26} D_{3h} symmetry conformation with term ^{5}A_{1} [2].

Quantum chemical ab initio investigations of the stability of the non-covalent fullerene complexes: C_{60} molecule + Li atom, two C_{60}, two C_{60} + CS_{2}, C_{60} + CS_{2}, C_{60} + C_{6}H_{6} were performed using Hartree-Fock (HF) and Density Functional Theory (DFT) methods in various basis sets [3]. The inclusion of electron correlation effect calculated by using DFT B3PW91 model during the optimization of Li atom position above hexagonal of C_{60} gives the smaller distance from the centre of C_{60} equal to 7.75 Å and large positive energy of formation equal to 4.452 kcal/mol in comparison with HF calculated distance 8.39 Å and energy of formation 1.810 kcal/mol. The positive energy of formation equal to 0.483 kcal/mol for optimized complex two C_{60} + one CS_{2} was found by HF. The presence of CS_{2} molecule stabilises this complex with the energy equal to 0.281 kcal/mol. Complexes: C_{60} + CS_{2}, C_{60} + C_{6}H_{6} do not possess the positive energy of formation.

The catalytic activation of tetrahedral P_{4} allotrope of elemental phosphorus by transition metal complexes 1) - 7) have been calculated and investigated using the HF and DFT methods in the 6-311G, LanL2MB and LanL2DZ basis sets.

The results of full geometry Berny optimization of complexes 4) - 7) shows that P_{4} molecule in the complexes transforms to the deformed pyramid - partially folded kite-like structures. The P-P bond in n^{2}-P of P_{4} in the 4) and 7) complexes has broken during the full geometry optimization due to the coordination of n^{2}-P to the central Pt atom. The HOMO of the optimized complexes lowered in comparison with not optimized complexes due to the large strains in not optimized complexes. The DFT B3PW91 model is better in comparison with HF for the calculations of coordination complexes [7]. The new series of transition metal complexes containing fullerene C_{60} molecule 8-14) was proposed for the catalytic activation of tetrahedral P_{4} allotrope of elemental phosphorus:

The investigations of electronic spectra calculations of all optimized complexes is doing by using ab initio HF CIS method. The full geometry optimization in the framework of HF and DFT methods are performing of new series of original complexes proposed by Dr. R. Abdreimova:

The quantum chemical calculations and investigations of the stability of twenty eight
photoactive charge transfer supramolecules constructed from disc-like pentayne
(pentakis(phenyle thynyl)phenyl) molecules with radicals R = -OC_{5}H_{11},
-CH_{3}, -CF_{3}, -CN and seven organic electron acceptor molecules: TNF,
TeNF, TCNQ, TN9(CN)_{2}F, TCNB, TeClBQ, TeFTCNQ were performed using the
MOPAC-PM3 method. All supramolecules have relatively small energetic gap, i. e. they are good
electron donors and good electron acceptors at the same time. Therefore these supramolecules
should be molecular photodiodes. Energies of formation are largest for supramolecules
constructed from disc-like pentayne with -CH_{3} radical and TeNF or
TN9(CN)_{2}F molecules - 2.16 and 2.20 kcal/mol respectively. It was
found that:

all investigated supramolecules: disc-like pentayne molecules::electron acceptor molecules are stable, possess dipole moments and are potential molecular photodiodes;

the order of decreasing stability of the above mentioned supramolecules with various radicals is: -CH_{3} > -OC_{5}H_{11} > -CF_{3} > -CN;

the order of decreasing stability of the supramolecules with various electron acceptor molecules is: TeN9(CN)_{2}F > TeNF > TNF > TeFTCNQ > TCNQ > TCNB > TeClBQ [1].

Molecular implementation (MI) of two, three, four variable logic functions, summators of neuromolecular networks, cells of molecular cellular automata, molecular trigger, devices of electronically genome regulation were designed based on results of semiempirical quantum chemical calculations of organic electron donor, electron insulator, electron acceptor and fullerene molecules [1, 4-6, 8, 9]. Complete set of sixteen MIs of two variable logic functions (for example: OR, AND, Implication, Equivalence, Difference, etc.) was designed and also proposed using MIs of two variable molecular logic function initial basic sets: {OR, AND, Negation} or {NOR} and, or {NAND}. We have described in more detail the designed MIs of:

two variable logic functions OR, NOR, AND, NAND (two sets: one designed from planar molecules and another - from fullerene molecules) , Converse Unitary Negation-1, Converse Unitary Negation-0, Unitary Negation-1, Unitary Negation-0, "0" and "1" Matrix Constants;

three variable logic functions AND, NAND, OR, NOR analogs;

four variable logic functions OR, NOR, AND, NAND analogs,

molecular cell that simulates one of Life figures,

summator of neuromolecular network that simulates sigmoidal behaviour of artificial neurone.

This was done based on quantum chemical investigations of organic photo-induced electron donor molecules:

carbazole, 3,6-dibromcarbazole, TeMePhDA, PhDA;

electron acceptor molecules: TCNQ, TCNB, TeClBQ, small empty and endohedral fullerene molecules: C_{60}, C_{28}, C_{28}H_{4}, C_{24}H_{2}, C_{20}, C_{20}H_{6}, A@C_{60}, A=Be, Zn, Cd and

electron insulator molecules by using MOPAC-7 programme package [1, 4-6].

We are investigating in more detail the electronic structure of above mentioned planar organic electron donor and electron acceptor molecules and series of fullerene C_{60} substituted derivatives: C_{60}CH_{2}, C_{60}C_{2}H_{4}, C_{60}C_{3}H_{6}, C_{60}C_{4}H_{8} using ab initio HF and DFT methods and designed new series of more correctly MIs of two variable logic functions OR, NOR, AND, NAND (two sets: one designed from planar molecules and another - from fullerene molecules) , Converse Unitary Negation-1, Converse Unitary Negation-0, Unitary Negation-1, Unitary Negation-0, "0" and "1" Matrix Constants based on geometry optimization procedure of above mentioned molecular devices. The electron hoping via the insulator bridges in the supermolecules: electron donor-bridge-electron acceptor phenomenon was investigated by using CNDO/S-Configuration Interaction method.

References

[1] Tamulis A., Stumbrys E., Tamulis V. and Tamuliene J., "Quantum Mechanical Investigations of Photoactive Molecules, Supermolecules, Supramolecules and Design of Basic Elements Molecular Computers", in NATO ASI series, High Technology; Vol. 9, Ed. by F. Kajzar, V. M. Agranovich and C. Y.-C. Lee, "Photoactive Organic Materials: Science and Applications", June 25-30, 1995, Avignon, France, Kluver Academic Publishers, Doderecht/Boston/London, 1996, p.p. 53-66.

[2] Balevicius L.M., Stumbrys E., Tamulis A., "Conformations and Electronic Structure of Fullerene C_{24} and C_{26} Molecules", Fullerene Science and Technology, 1997, vol. 5, No. 1, p.p. 85-96.

[3] Tamulis A., Tamuliene J. and Graja A., "Quantum Chemical ab initio Investigations of Non-Covalent Bonding Derivatives of Fullerene C_{60} and Li Atom or CS_{2}, C_{6}H_{6} Molecules", to be published in the journal Fullerene Science and Technology, vol. 6, No 6, November, 1988.

[4] Tamulis, A., Tamulis, V., "Molecular Electronics - Advanced Technology", Science and Arts of Lithuania, 1994, vol. 2, No 4, p.p. 40-47, (in Lithuanian).

[5] Tamulis A., Tamulis V., "Quantum Mechanical Design of Basic Elements of Molecular Computers", #8 Newsletter of International Society of Molecular Electronics and BioComputing, November 1997, p.p. 15-22.

[6] Tamulis A., Braga M., Klimkans A., "Quantum Chemical Investigation of Two Fullerene C_{60} Molecules", Fullerene Science and Technology, 1995, vol. 3, No. 5, p.p. 603-610.

[7] A. Tamulis, R. R. Abdreimova, J. Tamuliene, M. L. Balevicius, M. Peruzzini, "Quantum Mechanical ab initio Investigations of Oxidative P-O Coupling of Tetraphosphorus with Alcohol on Pt(IV, II) Halides", manuscript prepared for the publication in the Journal of Organometallic Chemistry, 1998.

[8] A. Tamulis, V. Tamulis, "Design of Basic Elements of Molecular Computers Based on Quantum Chemical Investigations of Photoactive Organic Molecules", Proceedings of the SPIE Photonics WEST® Conference on Optoelectronic Integrated Circuits II, held on 24-30 January, 1998, San Jose Convention Center, San Jose, California, U.S.A., Volume 3290, p.p. 315-324.

[9] A. Tamulis, V. Tamulis and J. Tamuliene, "Quantum Mechanical Design of Molecular Implementation of Two, Three and Four Variable Logic Functions for Electronically Genome Regulation", Viva Origino, vol. 26 (1998) 127-146.

Acknowledgements. Our research described in this summary was supported by the Lithuanian Government and in part by the Swedish Institute, Grants N LAM000, N LHW100 by the International Science Foundation, by the NATO Science Committee Guest Fellowships Programme 1994 No 5 Fellowships for Chemistry, by the Non-Profit Area of VIVAHOTELS® Research Project VIVAFIRENZE® and the European Commission contract ERBIC15CT960746.

^{*}Corresponding Address:
Dr. Arvydas Tamulis
Institute of Theoretical Physics and Astronomy
A. Gostauto 12, 2600 Vilnius, Lithuania
Phone: +(370-2)-620861; Faxes: +(370-2)-225361, 224694
e-mail:Tamulis@ITPA.lt
Website: htpp://www.itpa.lt/~tamulis/