A THEORETICAL STUDY ON THE STRUCTURAL, ELECTRONIC AND OPTICAL CHARACTERISTICS OF TETRAAZA MACROCYCLIC COMPLEX NUR HALIMATUS SAADIAH BINTI ABDULLAH UNIVERSITI SAINS ISLAM MALAYSIA A THEORETICAL STUDY ON THE STRUCTURAL, ELECTRONIC AND OPTICAL CHARACTERISTICS OF TETRAAZA MACROCYCLIC Nur Halimatus Saadiah Binti Abdullah Thesis submitted in partial fulfillment for the degree of MASTER OF SCIENCE UNIVERSITI SAINS ISLAM MALAYSIA September 2023 ii AUTHOR DECLARATION I hereby declare that the work in this thesis is my own except for quotations and summaries which have been duly acknowledged Date: Signature: Name: Name: Nur Halimatus Saadiah binti Abdullah Matric No: 3191469 Address: iii ACKNOWLEDGEMENTS Praise to the Allah s.w.t because his blessing I can successfully finished my research thesis entitled “A Theoretical Study on the Structural, Electronic and Optical Characteristics of Tetraaza Macrocyclic Complex”. Firstly, I would like to express my profound gratitude to my supervisor, Dr Lailatun Nazirah Ozair. With her continuous guidance, support and encouragement this work has been done perfectly on time. Besides, I would like to acknowledge of Dr Muhammad Mus’ab Anas Mohd Anas for his assistance and dedicated involvement in every step throughout the research process. Last but not least, a special thanks to my family and friends for their unconditional love and motivation throughout completing this research. iv ABSTRAK Pd(II) kompleks yang mengandungi ligan tetraaza makrosilik telah menjadi topik penting dalam kajian penyelidikan terkini terutama dalam bidang pemangkinan, aplikasi rawatan sisa, dan bioperubatan. Ciri paling unik ligan tetraaza makrosilik ialah zarah nitrogen tinggi daya pilih terhadap ion logam peralihan dan tinggi kecenderungan membentuk sebatian makrosilik. Kaedah konvensional sintesis ligan tetraaza makrosilik ialah menjadikan ion logam peralihan sebagai agen templat mempunyai masalah semasa proses nyahkompleks kerana ion templat terlalu stabil. Kemudian, kaedah sintesis tanpa templat diperkenalkan yang menghasilkan ligan tetraaza makrosilik dan sebatian logam terproton. Bagaimanapun, hingga kini, sangat terhad kajian teori secara spesifik dilaporkan ke atas interaksi logam-ligan semasa pengkompleksan berlaku. Oleh itu, kajian ini telah memeriksa struktur Pd(II) ligan tetraaza makrosilik dan mengkaji sifat elektronik melalui pengiraan teori fungsi ketumpatan. Geometri molekul menunjukkan zarah Pd(II) berjaya menyuaikan diri dalam ligan makrosilik dan interaksi logam-ligan menyumbang pada kestabilan Pd(II) ligan tetraaza makrosilik. Kemudian, sifat optikal Pd(II) ligan tetraaza makrosilik telah disiasat pada keadaan teruja menggunakan teori sandaran masa fungsi ketumpatan dalam medium gas mendapati sempadan orbital molekul menunjukkan mobiliti elektron yang tinggi kerana sikit tenaga yang diperlukan semasa proses pemindahan elektron. Tindak balas optikal terhadap Pd(II) ligan tetraaza makrosilik dalam medium heksana, toluene, kloroform, metanol, asetonitril dan air menggunakan formalisme persamaan integral oleh model polarasi kontinum menunjukkan perubahan bererti pada nilai-nilai jurang tenaga, puncak penyerapan, dan hiperpolarisasi berbanding dalam medium gas. v ABSTRACT Pd (II) complex containing tetraaza macrocyclic ligand has already been an important topic of current research studies, especially in catalysis, waste treatment application, and biomedical. The most unique properties of macrocycles containing nitrogen atoms are high selectivity towards transition metal ions and a high tendency to form macrocyclic compounds. The established method of synthesising tetraaza macrocyclic ligand by introducing a transition metal ion as a templating agent has demonstrated difficulties in the decomplexation process because template ions are too stable. Later, one pot synthesis of the non-template has been introduced resulting in protonated tetraaza macrocyclic ligand and metal complex. However, until today, there are limited theoretical studies that specifically reported on metal-ligand interaction in complexation. Therefore, this study examined the structure of the Pd(II) tetraaza macrocyclic ligand and further explored its electronic properties through density functional theory (DFT) calculation. The molecular geometry shows that the Pd(II) atom successfully fits in the macrocyclic ligand and metal-ligand interaction contributes to the stability of the Pd (II) tetraaza macrocyclic ligand. Then, the optical properties of Pd(II) tetraaza macrocyclic ligand were investigated at excited state using time- dependent density functional theory (TD-DFT) in gas medium observed frontier molecular orbitals indicate high electron mobility since only little energy is required for the electron transfer process. The optical responses on Pd (II) tetraaza macrocyclic ligand in hexane, toluene, chloroform, methanol, acetonitrile, and water environment using integral equation formalism of polarizable continuum model (IEF-PCM) show significant changes of the energy gap, absorption peaks, and hyperpolarizability values compared in gas medium. iv الملخص )CIBARA( SAHKHKALUM-LA قد أصبح موضوعا ًهاما ًفي الدراسات الذي يحتوي على معقد ماكروسيكليك تترازا )II( dPاالمركب البحثية الحالية، وخصوصا ً في مجالات الكاتاليز وتطبيقات معالجة النفايات والطب الحيوي. من بين الخصائص الفريدة للماكروسيكليك الذي يحتوي على ذرات النيتروجين هو انعتاقه العالي تجاه أيونات مركبات ماكروسيكلية. أثبتت الطريقة المثبتة لتخليق الماكروسيكليك المعادن الانتقالية وميلاه الكبير لتكوين تترازا باستخدام أيون المعدن الانتقالي كعامل قوالب صعوبات في عملية الفك تترتب عليها ثبات كبير. في وقت لاحق، تم تقديم تخليق في مرحلة واحدة بدون قوالب، مما أدى إلى الحصول على الماكروسيكليك المستخدم والمركب المعدني. ومع ذلك، حتى اليوم، هناك دراسات نظرية محدودة تقريرت خصوصا ً المحمض عن التفاعل بين المعدن والمركب في العملية التفاعلية. لذا، يهدف هذا البحث إلى دراسة هندسة مركب لكثافي واستكشاف خصائصه الإلكترونية من خلال حساب نظرية الوظائف ا )II(dPالماكروسيكليك تناسب الماكروسيكليك وأن التفاعل بين المعدن والمركب )II(dP. تظهر هندسة الجزيء أن ذرة FD . بعد ذلك، تمت دراسة الخواص البصرية )II(dPيساهم في استقرار مركب الماكروسيكليك -DTمدة (في الحالة المثارة باستخدام نظرية الوظائف الكثافية الزمنية المعت )II(dPللماكروسيكليك في وسط الغاز، مما يشير إلى حركية إلكترونية عالية نظرا ًلاحتياج النقل الإلكتروني إلى كمية طاقة TFD في الهكسان، والتولين، والكلوروفورم، )II(dPصغيرة جدا.ً تظهر الاستجابات البصرية لماكروسيكليك -FEI( كامل للنظام المتغير القابل للتواصل والميثانول، والأستونيتريل، والماء باستخدام نموذج معادلة الت تغييرات كبيرة في الفجوة الطاقوية وذروات الامتصاص وقيم الانقطاع الهايبربولاريزابلية مقارنة )MCP بوسط الغاز. vii TABLES OF CONTENTS CONTENT PAGE AUTHOR DECLARATION ii ACKNOWLEDGEMENTS iii ABSTRAK iv ABSTRACT v AL-MULAKHKHAS vi TABLES OF CONTENTS vii LIST OF TABLES ix LIST OF FIGURES xi LIST OF APPENDICES xii LIST OF ABBREVIATIONS xiii INTRODUCTION 1 1.1 Background 1 1.2 Problem Statement 2 1.3 Research Question 3 1.4 Hypothesis 3 1.5 Objectives 4 1.6 Scope of Research 4 LITERATURE REVIEW 6 2.1 Structural and Electronic Properties of Tetraaza Macrocyclic Ligand 9 2.1.1 Geometry Optimization 9 2.1.2 Natural Bond Orbital Analysis 10 2.1.3 Molecular Electrostatic Potential Surface 12 2.2 Optical Properties of Tetraaza Macrocyclic Ligand 14 2.2.1 Frontier Molecular Orbital Study 14 2.2.2 UV-VIS Spectroscopy 17 2.2.3 Non-Linear Optical Study 20 RESEARCH METHODOLOGY 26 3.1 Exchange-correlation 29 3.2 Basis Set 30 3.3 Polarizable Continuum Model 31 3.4 Hardware 33 3.5 Software 33 3.6 Ground State Calculation 34 3.7 Excited State Calculation 36 3.8 Solvation Model Calculation 38 RESULTS 40 4.1 Structural and Electronic Properties at Ground State 40 4.2 Optical Properties at Excited State in Gas Phase 51 4.3 Optical Properties of Pd(II) Complex at Excited State in Solvent Phase 55 4.3.1 Electronic Spectra 55 viii 4.3.2 Frontier Molecular Orbital 60 4.3.3 Non-Linear Optical Properties 63 CONCLUSION 66 REFERENCES 68 APPENDICES 76 ix LIST OF TABLES Tables Page Table 2.1: Summary of Findings on Energy Gap of Tetraaza Macrocyclic Complex 16 Table 2.2: The First Hyperpolarizabilities (a.u) and Dipole Moments (Debye) of All Complexes 22 Table 2.3: Summary of Finding on NLO Value of Various Compund 25 Table 3.1: Classification of Computational Chemistry Methods 28 Table 3.2: Solvents list and dielectric constant value, ε 33 Table 3.3: Gaussian16 Input of Tetraaza Macrocylic Ligand and Its Complex 35 Table 3.4: Gaussian16 Input of Pd(II) Complex At Excited State 36 Table 3.5: Gaussian16 Input of Pd(II) Complex in Solvent Phase 39 Table 4.1: Total Molecular Energy (Hartree) Using Different Basis Set 41 Table 4.2: Selected Bond Lengths (A) 42 Table 4.3: Selected Bond Lengths (A) and Angles (deg) 45 Table 4.4: Occupancy and Hybrids of Tetraaza Macrocyclic Ligand 46 Table 4.5: Occupancy and Hybrids of Pd(II) Complex 47 Table 4.6: Second Order Perturbation Theory Analysis on Tetraaza Macrocyclic Ligand 48 Table 4.7: Second Order Perturbation Theory Analysis on Pd(II) Complex 49 Table 4.8: TD-DFT data of HOMO (H), HOMO(H-12), LUMO (L), LUMO-1(L+1), LUMO-2(L+2), LUMO-3(L+3), LUMO- 6(L+6) Molecular Orbitals of Pd(II) Complex in Gas Phase 52 Table 4.9: Summarized All Important Non-Linear Optical Properties of the Pd(II) Complex 54 Table 4.10: TD-DFT data of HOMO-2(H+2), HOMO-4(H+4), LUMO (L), LUMO-1(L+1), LUMO-2(L+2), LUMO-3(L+3) Molecular Orbitals in Methanol 57 Table 4.11: TD-DFT data of HOMO-2(H+2), LUMO (L), LUMO-1(L+1), LUMO-2(L+2), LUMO-5(L+5) in Acetonitrile 58 x Table 4.12: TD-DFT data of LUMO-1(L+1), LUMO-2(L+2), LUMO- 3(L+3), and LUMO-4(L+4) in Water 58 Table 4.13: TD-DFT data of HOMO-2(H+2), HOMO-3(H+3), HOMO- 4(H+4), LUMO-1(L+1), and LUMO-2(L+2) in Chloroform 59 Table 4.14: TD-DFT data of HOMO-1(H+1), HOMO-2(H+2), LUMO- 1(L+1), and LUMO-2(L+2) in Toluene 60 Table 4.15: TD-DFT data of HOMO-1(H+1), HOMO-2(H+2), HOMO- 3(H+3), LUMO-1(L+1), and LUMO-2(L+2) in Hexane 60 Table 4.16: The Dipole Moment and values of First Hyperpolarizability in Polar Solvents 64 Table 4.17: The Dipole Moment and values of First Hyperpolarizability in Non-Polar Solvents 65 xi LIST OF FIGURES Figures Page Figure 2.1: Neutral (left) and Protonated (right) 14-Membered Tetraaza Macrocyclic Ligand 8 Figure 2.2: Molecular structure of cation Cu(II) tetraaza macrocyclic complex with bromide counter anion drawn at 50% probability ellipsoids (reprinted from reference with permission from authors) Introduction 8 Figure 2.3: Frontier molecular orbital of Pyr-2-Bt-PdCl2 15 Figure 2.4: The Possible Electron Transition from Full Orbital to Empty Orbital 18 Figure 2.5: Illustration of Second Harmonic Generation 21 Figure 2.6: Structural Formulas for Mono Schiff-Base M(II) (M = Ni, Pd, Pt) Complexes 22 Figure 3.1: Flowchart of the Ground State Calculation 35 Figure 3.2: Flowchart of the Excited State Calculation 37 Figure 3.3: Flowchart of the Solvation Model Calculation 39 Figure 4.1: The Molecular Geometries of the Tetraaza Macrocyclic Ligand 43 Figure 4.2: The Molecular Geometries of Pd(II) Tetraaza Macrocyclic Ligand 44 Figure 4.3: Electrostatic Potential Distribution on Protonated Tetraaza Macrocyclic Ligand (left) and Cationic Pd(II) Complex (right) 50 Figure 4.4: Absorption Spectra of Pd(II) Complex in Gas Phase 52 Figure 4.5: The FMO with Energies of Pd(II) Complex 53 Figure 4.6: Absorption Spectra of Pd(II) Complex In Different Solvent 56 Figure 4.7: The FMO and the Energy Gaps of Pd(II) Tetraaza Macrocyclic Ligand in Polar Solvents (a) and Non-Polar Solvents (b) 62 xii LIST OF APPENDICES Appendices Page Appendix 1: Input file of Tetraaza macrocyclic ligand at ground state 76 Appendix 2: Input file of Pd(II) tetraaza macrocyclic ligand at ground state 78 Appendix 3: Input file of Pd(II) tetraaza macrocyclic ligand at excited state in gas 80 Appendix 4: Input file of Pd(II) tetraaza macrocyclic ligand at excited state in solvent phase 82 xiii LIST OF ABBREVIATIONS AM1 Austin model 1 B3LYP Becke, three-parameters, Lee-Yang-Parr CC Coupled Cluster theory CI Configuration Interaction DFT Density functional theory ECP effective core potential FMO Frontier molecular orbital GGA Generalized Gradient approximation HF Hartree-Fock HOMO Highest occupied molecular orbital IEF-PCM integral equation formalism of polarizable continuum model INDO intermediate neglect of differential overlap methods LANL2DZ Los Alamos National Laboratory 2 Double- Zeta LDA Local Density approximation LUMO Lowest unoccupied molecular orbital MM2 molecular mechanics 2 MM3 molecular mechanics 3 MMFF94 Merck molecular force field 94 NLO Non-linear optical properties Pd Palladium PM3 parametric method 3 STO-3G Slater-type and Gaussian-type atomic orbitals TD-DFT Time dependent- density functional theory UV-vis Ultraviolet-visible