The study explores the realization of tunable topological phases in spin-1/2 alternating-exchange (AH) Heisenberg chains based on nanographene. By covalently linking Clar's goblets, each hosting two antiferromagnetically coupled unpaired electrons, the researchers construct AH chains with antiferromagnetic couplings \(J_1\) and \(J_2\). Using scanning tunneling microscopy (STM), they control the chain lengths, parities, and exchange-coupling terminations, and probe the magnetic response through inelastic tunneling spectroscopy. The investigation confirms the gapped nature of bulk excitations, known as triplons, and extracts their dispersion relation from the spatial variation of tunneling spectral amplitudes. Depending on the parity and termination of the chains, varying numbers of in-gap \(S = \frac{1}{2}\) edge spins are observed, allowing the determination of the degeneracy of distinct topological ground states (1, 2, or 4). The exponential decay of spin correlations is monitored, and theoretical calculations support the findings. This work presents a phase-controlled many-body platform, opening avenues for the development of spin-based quantum devices.The study explores the realization of tunable topological phases in spin-1/2 alternating-exchange (AH) Heisenberg chains based on nanographene. By covalently linking Clar's goblets, each hosting two antiferromagnetically coupled unpaired electrons, the researchers construct AH chains with antiferromagnetic couplings \(J_1\) and \(J_2\). Using scanning tunneling microscopy (STM), they control the chain lengths, parities, and exchange-coupling terminations, and probe the magnetic response through inelastic tunneling spectroscopy. The investigation confirms the gapped nature of bulk excitations, known as triplons, and extracts their dispersion relation from the spatial variation of tunneling spectral amplitudes. Depending on the parity and termination of the chains, varying numbers of in-gap \(S = \frac{1}{2}\) edge spins are observed, allowing the determination of the degeneracy of distinct topological ground states (1, 2, or 4). The exponential decay of spin correlations is monitored, and theoretical calculations support the findings. This work presents a phase-controlled many-body platform, opening avenues for the development of spin-based quantum devices.