\textbf{Unusual features of magnetism in transition-metal-doped phthalocyanines C}$_{\mathrm{\mathbf{32}}}$\textbf{H}$_{\mathrm{\mathbf{16}}}$\textbf{N}$_{\mathrm{\mathbf{8}}}$\textbf{TM (TM }$=$\textbf{ Mn, Fe, Co, Ni, Cu)}

Transition-metal-doped phthalocyanines (TMPc), semiconductors with potential optoelectronic applications [1], are planar molecules with the TM atom at the center bound to four N atoms and forming a linear chain along the monoclinic b-axis. Because of this symmetry, the ground states of TMPc often violate the Hunds' rules; e.g. the S $=$ 3/2 state for d$^{\mathrm{5}}$ Mn(II) in $\beta $-MnPc, S $=$ 1/2 state for the d$^{\mathrm{7}}$ Co(II) in $\beta $-CoPc, and S$=$0 for Ni(II) in NiPc. The magnetic properties of TMPc are also affected by the stack angle $\delta $ between the orientation of the molecular plane and the b-axis, $\delta $ being 65\textdegree (45\textdegree ) for $\alpha $ ($\beta )$ phase [2]. For $\beta $-CoPc, our M vs. T data fits well with the Bonner-Fisher model for S $=$ 1/2 AFM Heisenberg linear chain [3] yielding the Co$^{\mathrm{2+}}$-Co$^{\mathrm{2+}}$ exchange constant J/k$_{\mathrm{B}}$ $=$ - 1.5 K. For $\beta $-MnPc , a long-presumed ferromagnet with T$_{\mathrm{C}} \quad \approx $ 9 K [4], our magnetic studies show it to be an Ising chain magnet with Arrhenius magnetic relaxation governed by J/k$_{\mathrm{B}} \quad =$ 2.6 K and the zero-field splitting D/k$_{\mathrm{B}}$ $=$ 8.3 K. In $\beta $-MnPc, the absence of $\lambda $-type peak in specific heat and no peaks in ac susceptibilities near the quoted T$_{\mathrm{C}}$ $\approx $ 9 K confirms the absence of long range order (LRO). Instead we argue that LRO is absent in $\beta $-MnPc as D \textgreater J makes the spins in a chain parallel but canted with respect to spins in neighboring chains. [1]G. Mattioli et al, Phys. Rev. Lett. 101, 126805 (2008); [2]Z. Wang et al, IEEE Trans. Mag. 51, 2700104(2015); [3]J. Bonner {\&} M. Fisher, Phys. Rev. 135, A640 (1964); [4]Y. Taguchi et al, J. Magn. Magn. Mater.301, 1229 (2007).