Spectroscopic Analysis of Therapeutic Drugs Laura Perdisatt , Christine O’Connor, Samar Moqadasi, Luke O’Neill DT203/4 Forensic and Environmental Analysis School of Chemical and Pharmaceutical Sciences, DIT [email protected]

1. Introduction

The aim of this project was to investigate the photochemistry of three new Ruthenium (II) complexes as possible therapeutics and their associated ligands. The objectives were to use the following spectroscopic techniques: Absorption, Emission and Raman spectroscopy. Luminescent lifetime measurements were obtained by laser studies (Nd:YAG laser and Time coupled single photon counting (TCSPC) ).

Complexes Ru(bpy)

2

fmp Ru(bpy)

2

mfmp Ru(bpy)

2

NO

2

-mp Ligands fmp mfmp NO

2

-mp

R2 R1 N N N N N Ru N N N

Table 1:

All The complexes and ligands investigated in this project.

Figure 1

: The ruthenium complex structure where R1& R2= (H, CHO), (CHO, H), (H, NO 2 ) for fmp, mfmp and NO 2 -mp respectively

2. Experimental Details & Absorption/Emission Spectroscopy Results

A concentration range of 0.1 mM to 0.025 mM were made of each complex and ligand.

The complexes were thermally stable and soluble in MeCN and the ligands soluble in DMSO. The extinction coefficients were determined along with the quantum yields for the complexes relative to a standard Ru(bpy) 3 Cl 2 and the results are shown in Table 2. The emission spectra of each of the complexes can be seen below in figure 2.

I n t e n s i t y

200 180 160 140 120 100 80 60 40 20 0 480 530 580

Wavelength (nm)

630 680 Ru(bpy)2 fmp Ru(bpy)2 mfmp Ru(bpy)2 NO2-mp Ru(bpy)3Cl2

Figure 2:

Emission Spectra of all the complexes and standard at 0.1 mM in MeCN excited at their λ max

Compound Name Ru(bpy)

2

fmp Ru(bpy)

2

mfmp Ru(bpy)

2

NO

2

-mp Std: Ru(bpy)

3

Cl

2

fmp mfmp NO

2

-mp Abs λ

max

(nm) 457 457 456 451 284 284 294 Extinction coefficient 10,600 12,480 22,480 12,108 14,280 25,320 20,080 Emission λ

max

(nm) 597 597 600 602 424.5

425 592 Quantum Yield (Φ

f

) 0.29

0.21

0.08

0.20

n/a n/a n/a Table 2:

Absorption and Emission λmax with corresponding extinction coefficients and quantum yields of the Ru(II) complexes and ligands

3. Laser Studies

The luminescent lifetimes were determined for each of the complexes under two conditions aerated and degassed. The aerated lifetimes were found to be significantly shorter than the degassed solutions and this is shown in table 3.

I n t e n s i t y

50 45 40 35 30 25 20 15 10 5 0 560 610

Complex Name Ru(bpy)

2

fmp Ru(bpy)

2

mfmp Ru(bpy)

2

NO

2

-mp

(a)

660

Wavelength (nm)

710 760

(τ) Lifetime ns (Nd:YAG) 160 (204) 183 (286) 102 (164) Table 3

Comparison of aerated and degassed(in brackets) luminescent lifetimes from both laser techniques

4. Raman Spectroscopy

Raman Spectroscopy was completed on one of the complexes Ru(bpy) 2 NO 2 -mp as a powder at a laser line of 785 nm. This laser line proved to have one of the weakest fluorescence signals in comparison to the others as an emission study was completed by exciting the complexes at various wavelengths (488 nm, 514 nm, 540 nm, 633 nm, 660 nm & 785 nm.). The highest fluorescence signal was observed at 488 nm which was expected as its very close to their absorption ( λmax).

3500 488nm 514nm 540nm

(b)

3000 2500 2000 1500 1000 500 0

(τ)Lifetime ns

500

(TCSPC) 155 182 96

Ru(bpy)2NO 2 -mp 1000 1500 Wavenumber Shift(cm -1 ) 2000 2500

Figure 3: (a)

Ru(bpy) 2 NO 2 -mp emission intensity at excitation wavelengths of 488 nm (green), 514 nm (blue) and 540 nm (red).

(b)

The Raman Spectrum at 785 nm laser line.

5. Conclusion

Absorption and Emission studies were completed on each of the Ru (II) complexes and ligands and from this the extinction coefficients and quantum yields were calculated. The luminescent lifetimes were determined for each of the ruthenium (II) complexes by two laser techniques ( Nd:YAG and TCSPC). Preliminary Raman studies was completed on the complex, Ru(bpy) 2 NO 2 -mp.

6. Acknowledgments

A huge thank you to Christine their help O’Connor, Samar Moqadasi and Luke O'Neill for all